diabetestalk.net

Can Glucogenic Amino Acids Be Used To Make Glucose?

Glucogenic And Ketogenic Amino Acids

Glucogenic And Ketogenic Amino Acids

Amino acids can be classified as being “glucogenic” or “ketogenic” based on the type of intermediates that are formed during their breakdown or catabolism. The catabolism of glucogenic amino acids produces either pyruvate or one of the intermediates in the Krebs Cycle. The catabolism of ketogenic amino acids produces acetyl CoA or acetoacetyl CoA (see Figure 1). There is a rare medical condition in which a person is deficient in the pyruvate dehydrogenase enzyme that converts pyruvate to acetyl CoA – a precursor for the Krebs Cycle. Signs and symptoms vary, but there are generally two main manifestations. First, patients can have an elevated blood lactate (lactic acid) level. Second, patients may have neurological defects, including microcephaly (a small head circumference) and/or mental retardation. Treatment is currently limited and not very effective. Moreover, damage to the brain is often irreversible. Your biochemistry study partner looks at Figure 1 and exclaims, “This doesn’t make sense - why can’t acetyl-coA and the ketogenic amino acids be converted back to pyruvate to create glucose using pyruvate dehydrogenase?” With your knowledge of basic chemistry, you answer: Continue reading >>

Glucogenic Amino Acids

Glucogenic Amino Acids

DOUGLAS C. HEIMBURGER MD, in Handbook of Clinical Nutrition (Fourth Edition) , 2006 The major aim of protein catabolism during a state of starvation is to provide the glucogenic amino acids (especially alanine and glutamine) that serve as substrates for endogenous glucose production (gluconeogenesis) in the liver. In the hypometabolic/starved state, protein breakdown for gluconeogenesis is minimized, especially as ketones become the substrate preferred by certain tissues. In the hypermetabolic/stress state, gluconeogenesis increases dramatically and in proportion to the degree of the insult to increase the supply of glucose (the major fuel of reparation). Glucose is the only fuel that can be utilized by hypoxic tissues (anaerobic glycolysis), by phagocytosing (bacteria-killing) white cells, and by young fibroblasts. Infusions of glucose partially offset a negative energy balance but do not significantly suppress the high rates of gluconeogenesis in the catabolic patient. Hence, adequate supplies of protein are needed to replace the amino acids utilized for this metabolic response. In summary, the two physiologic states represent different responses to starvation. The hypometabolic patient, who conserves body mass by reducing the metabolic rate and using fat as the primary fuel (rather than glucose and its precursor amino acids), is adapted to starvation. The hypermetabolic patient also uses fat as a fuel but rapidly breaks down body protein to produce glucose, the fuel of reparation, thereby causing loss of muscle and organ tissue and endangering vital body functions. Joerg Klepper*, in Handbook of Clinical Neurology , 2013 Gluconeogenesis, predominantly in the liver, generates glucose from noncarbohydrate substrates such as lactate, glycerol, and glucogenic amino acid Continue reading >>

Amino Acid Metabolism

Amino Acid Metabolism

Amino acids are categorized into two types - non-essential amino acids (can be synthesized by the body) and essential amino acids which cannot, and have to be provided from the diet. The non-essential amino acids are glycine, alanine, serine, asparagine, aspartic acid, glutamine, glutamic acid, proline, cysteine, tyrosine and arginine. The essential amino acids include valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, threonine, lysine and histidine. The amino acids arginine, methionine and phenylalanine are considered essential because their rate of synthesis is insufficient to meet the growth needs of the body. Most of synthesized arginine is cleaved to form urea. Methionine is required in large amounts to produce cysteine if the latter amino acid is not adequately supplied in the diet. Similarly, phenylalanine is needed in large amounts to form tyrosine if the latter is not adequately supplied in the diet. The amino acid pool comes from protein degradation in the gastro-intestinal tract, intracellular protein degradation and de novo synthesis and is used in protein synthesis and metabolism. Each amino acid type has its own metabolic fate and specific functions. Not only does this metabolic process generate energy, but it also generates key intermediates for the biosynthesis of certain non-essential amino acids, glucose and fat. Synthesis of non-essential amino acids Essential amino acids - valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, threonine, lysine and histidine - cannot be synthesized by the human body and thus have to be provided from the diet. While the amino acids arginine, methionine and phenyalanine can be synthesized by mammalian cells they are considered dietary essentials as their rate of synthesis is insufficient Continue reading >>

Difference Between Glucogenic And Ketogenic Amino Acids

Difference Between Glucogenic And Ketogenic Amino Acids

Home Science Chemistry Biochemistry Difference Between Glucogenic and Ketogenic Amino Acids Difference Between Glucogenic and Ketogenic Amino Acids Main Difference Glucogenic vs Ketogenic Amino Acids Amino acids are the building blocks of proteins and polypeptides . These are organic compounds composed of C, H, O and N atoms. Amino acids can be categorized into two main groups as essential amino acids and non-essential amino acids . Essential amino acids are amino acids that cannot be synthesized in our body whereas non-essential amino acids are amino acids that can be synthesized by the human body. In addition, amino acids can be classified into three groups based on the catabolism . They are Glucogenic amino acids, Ketogenic amino acids and mixed amino acids (both Glucogenic and Ketogenic). The main difference between glucogenic amino acids and ketogenic amino acids is thatglucogenic amino acids can be converted into pyruvate or other glucose precursors whereas ketogenic amino acids can be converted into acetyl CoA and acetoacetylCoA. Key Terms: Amino Acids, Essential Amino Acids, Glucogenic, Gluconeogenesis, Ketogenesis, Ketogenic, Polypeptides, Proteins Glucogenic amino acids are amino acids that can be converted into glucose via gluconeogenesis . In amino acid catabolism, Glucogenic amino acids form pyruvate or other glucose precursors as an intermediate. Here, other glucose precursors include alpha-ketoglutarate, succinyl Co-A, Fumarate, and oxaloacetate. Almost all essential and non-essential amino acids (except lysine and leucine- these are also essential amino acids but are Ketogenic amino acids) are Glucogenic amino acids. Therefore, Glucogenic amino acids include alanine, arginine, asparagine, aspartic, cysteine, glutamic, glutamine, glycine, histidine, meth Continue reading >>

Protein Metabolism - Welcome To Bio Stud...

Protein Metabolism - Welcome To Bio Stud...

The figure above show the overall summary of metabolism, in this site we will only discuss about proteins (amino acids) metabolism. obtained from essential or normal protein break down. Ketogenic & glucogenic amino acids (energy) Proteins degraded when the body's energy source are low and being used as an alternative energy source. Called as ketogenic and glucogenic. When energy sources are high, both ketogenic and glucogenic amino acids are ocnverted to fatty acids through the intermediate acetyl CoA. ketogenic amino acids can produce ketones when energy sources are low. degraded directly to ketone bodies such as acetoacetate (acetyl CoA). acetoacetate can be metabolized by the brain and muscle for energy when blood glucose is low. acetoacetate cannot be used in gluconeogenesis since acetyl CoA cannot be converted directly to oxaloacetate (OAA). glucogenic amino acids can be degraded to pyruvate or an intermediate in the Krebs Cycle. can produce glucose under certain conditions of low glucose. also called gluconeogenesis/ production of glucose from pyruvate or other intermediate in the Krebs Cycle. release energy that later being used in anabolism Continue reading >>

Glucogenic Amino Acids Archives - Tuscany Diet

Glucogenic Amino Acids Archives - Tuscany Diet

Gluconeogenesis is a metabolic pathway that leads to the synthesis of glucose from pyruvate and other non-carbohydrate precursors, even in non-photosynthetic organisms. It occurs in all microorganisms, fungi, plants and animals, and the reactions are essentially the same, leading to the synthesis of one glucose molecule from two pyruvate molecules. Therefore, it is in essence glycolysis inreverse, which instead goes from glucose to pyruvate, and shares seven enzymes with it. Glycogenolysis is quite distinct from gluconeogenesis: it does not lead to de novo production of glucose from non-carbohydrate precursors, as shown by its overall reaction: Glycogen or (glucose)n n glucose molecules The following discussion will focus on gluconeogenesis that occurs in higher animals, and in particular in the liver of mammals. Gluconeogenesis is an essential metabolic pathway for at least two reasons. It ensures the maintenance of appropriate blood glucose levels when the liver glycogen is almost depleted and no carbohydrates are ingested. Maintaining blood glucose within the normal range, 3.3 to 5.5 mmol/L (60 and 99 mg/dL), is essential because many cells and tissues depend, largely or entirely, on glucose to meet their ATP demands; examples are red blood cells, neurons, skeletal muscle working under low oxygen conditions, the medulla of the kidney, the testes, the lens and the cornea of the eye, and embryonic tissues. For example, glucose requirement of the brain is about 120 g/die that is equal to: over 50% of the total body stores of the monosaccharide, about 210 g, of which 190 g are stored as muscle and liver glycogen , and 20 g are found in free form in body fluids; about 75% of the daily glucose requirement, about 160 g. During fasting, as in between meals or overnight, the Continue reading >>

Carbon Atoms Of Degraded Amino Acids Emerge As Major Metabolic Intermediates - Biochemistry - Ncbi Bookshelf

Carbon Atoms Of Degraded Amino Acids Emerge As Major Metabolic Intermediates - Biochemistry - Ncbi Bookshelf

Fates of the Carbon Skeletons of Amino Acids. Glucogenic amino acids are shaded red, and ketogenic amino acids are shaded yellow. Most amino acids are both glucogenic and ketogenic. 23.5.1. Pyruvate as an Entry Point into Metabolism Pyruvate is the entry point of the three-carbon amino acidsalanine, serine, and cysteineinto the metabolic mainstream ( Figure 23.22 ). The transamination of alanine directly yields pyruvate. Pyruvate Formation from Amino Acids. Pyruvate is the point of entry for alanine, serine, cysteine, glycine, threonine, and tryptophan. As mentioned previously ( Section 23.3.1 ), glutamate is then oxidatively deaminated, yielding NH4+ and regenerating -ketoglutarate. The sum of these reactions is Another simple reaction in the degradation of amino acids is the deamination of serine to pyruvate by serine dehydratase ( Section 23.3.4 ). Cysteine can be converted into pyruvate by several pathways, with its sulfur atom emerging in H2S, SCN-, or SO32-. The carbon atoms of three other amino acids can be converted into pyruvate. Glycine can be converted into serine by enzymatic addition of a hydroxymethyl group or it can be cleaved to give CO2, NH4+, and an activated one-carbon unit ( Section 24.2.6 ). Threonine can give rise to pyruvate through the intermediate aminoacetone. Three carbon atoms of tryptophan can emerge in alanine, which can be converted into pyruvate. 23.5.2. Oxaloacetate as an Entry Point into Metabolism Aspartate and asparagine are converted into oxaloacetate, a citric acid cycle intermediate. Aspartate, a four-carbon amino acid, is directly transaminated to oxaloacetate. Asparagine is hydrolyzed by asparaginase to NH4+ and aspartate, which is then transaminated. Recall that aspartate can also be converted into fumarate by the urea cycle ( Continue reading >>

Why Can Fatty Acids Not Be Converted Into Glucose? : Mcat

Why Can Fatty Acids Not Be Converted Into Glucose? : Mcat

Rudeness or trolling will not be tolerated. Be nice to each other, hating on other users won't help you get extra points on the MCAT, so why do it? Do not post any question information from any resource in the title of your post. These are considered spoilers and should be marked as such. For an example format for submitting pictures of questions from practice material click here Do not link to content that infringes on copyright laws (MCAT torrents, third party resources, etc). Do not post repeat "GOOD LUCK", "TEST SCORE", or test reaction posts. We have one "stickied" post for each exam and score release day, contain all test day discussion/reactions to that thread only. Do not discuss any specific information from your actual MCAT exam. You have signed an examinee agreement, and it will be enforced on this subreddit. Do not intentionally advertise paid products or services of any sort. These posts will be removed and the user banned without warning, subject to the discretion of the mod team Learn More All of the above rules are subject to moderator discretion C/P = Chemical and Physical Foundations of Biological Systems CARS = Critical Analysis and Reasoning Skills B/B = Biological and Biochemical Foundations of Living Systems P/S = Psychological, Social, and Biological Foundations of Behavior Continue reading >>

What Is The Structural Difference Between Ketogenic Amino Acids And Glucogenic Amino Acids?

What Is The Structural Difference Between Ketogenic Amino Acids And Glucogenic Amino Acids?

1) Please edit the question turning your attention to punctuation. 2) Out of the blue I do not know what ketogenic and glucogenic amino acids are. Please edit your question to tell us this difference. (Editing a question (substantially!) is a much better way to attract attention and receive answers than posting an NAA-answer which will be deleted.) Jan Apr 30 '16 at 17:10 Standard amino acids are degraded to one of seven metabolic intermediates: pyruvate, -ketoglutarate, succinyl-CoA, fumarate, oxaloacetate, acetyl-CoA, or acetoacetate. The amino acids may therefore be divided into two groups based on their catabolic pathways: whose carbon skeletons are degraded to pyruvate, -ketoglutarate, succinyl-CoA, fumarate, or oxaloacetate and are therefore glucose precursors. whose carbon skeletons are broken down to acetyl-CoA or acetoacetate and can thus be converted to ketone bodies or fatty acids. The amino acids degraded to acetyl-CoA and acetoacetyl-CoA are used in the citric acid cycle, but mammals cannot synthesize glucose from acetyl-CoA. This fact is the source of the distinction between glucogenic and ketogenic amino acids. Glucogenic amino acids can be converted to glucose, with oxaloacetate as an intermediate, but ketogenic amino acids cannot be converted to glucose. Strictly speaking, whether an amino acid is regarded as being glucogenic, ketogenic, or both depends partly on the observer. This classification is not universally accepted, because different quantitative criteria are applied will identify the degradation pathways by the entry point into metabolism. I would also attribute to things like availability of feasible pathways, enzymes etc (for instance alanine is glucogenic because its transamination product, pyruvate can be converted to glucose via gluconeo Continue reading >>

Glucogenic Amino Acid | Definition Of Glucogenic Amino Acid By Medical Dictionary

Glucogenic Amino Acid | Definition Of Glucogenic Amino Acid By Medical Dictionary

Glucogenic amino acid | definition of Glucogenic amino acid by Medical dictionary the monovalent radical NH2, when not united with an acid radical. amino acid any of a class of organic compounds containing the amino (NH2) and the carboxyl (COOH) groups, occurring naturally in plant and animal tissues and forming the chief constituents of protein. Twenty amino acids are necessary for protein synthesis. Eleven (the nonessential amino acids) can be synthesized by the human body and thus are not specifically required in the diet: alanine , arginine , asparagine , aspartic acid , cysteine , glutamic acid , glutamine , glycine , proline , serine , and tyrosine . Nine (the essential amino acids) cannot be synthesized by humans and thus are required in the diet: histidine , isoleucine , leucine , lysine , methionine , phenylalanine , threonine , tryptophan , and valine . Structural formulas for some representative amino acids. From Applegate, 2000. Protein foods that provide the essential amino acids are known as complete proteins; these include proteins from animal sources, such as meat, eggs, fish, and milk. Proteins that cannot supply the body with all the essential amino acids are known as incomplete proteins; these are the vegetable proteins most abundantly found in legumes (peas and beans), as well as certain grains. Because different incomplete proteins lack different amino acids, specific combinations can provide all of the essential amino acids. In certain inherited or acquired disorders of metabolism, specific amino acids accumulate in the blood ( aminoacidemia ) or are excreted in excess in the urine ( aminoaciduria ). Urinary amino acid levels are increased in liver disease, muscular dystrophies, phenylketonuria (PKU), lead poisoning, and folic acid deficiency. An Continue reading >>

Amino Acid Metabolism:

Amino Acid Metabolism:

Humans ingest more protein (amino acids) than they need for replacement of endogenous proteins. These excess amino acids can not be stored and thus are catabolized (metabolized). Ultimate Fate of the carbon from excess amino acids: CO2, and energy (ATP) via TCA cycle and respiratory chain Glucogenic- amino acids which can be converted into glucose (CHO producing), Pyruvate or a TCA cycle intermediate that can be converted to OAA is produced in the final step of its metabolism. Ketogenic- amino acids which can be converted into fat (fat producing), Acetyl CoA or Acetoacetyl CoA is produced in the final step of their metabolism. (Acetyl CoA condenses with OAA so the net gain of OAA is zero since one molecule is consumed for each molecule of Acetyl CoA produced) Demonstrates a number of important features common to Glucogenic and Ketogenic pathways: (3) the possibility of inborn errors of metabolism at multiple steps [1] Phenylalanine Hydroxylase: Phe -----> Tyr Co-factor: Tetrahydrobiopterin, synthesized by animals and other microorganisms. Deficiencies: Phenylketonuria (PKU, common inborn error in metabolism), results in elevations of Phe, which if very high, prolonged --> permanent neurologic damage Solution: dietary restriction of Phe, all newborns screened to detect PKU --> low Phe diet Tetrahydrobiopterin Deficiencies: defects in synthesis can also result in elevations of blood Phe and severe neurologic disorders. [2] Tyrosine Aminotransferase: Tyr -----> p-Hydroxyphenylpyruvate Deficiencies: elevated blood Tyr (but not Phe since it is an irreversible reaction) ---> Tyr crystals form in tissues (cornea, palms, soles) [3] p-Hydroxyphenylpyruvate Oxidase: p-Hydroxyphenylpyruvate -----> Homogentisate [4] Homogentisate Oxidase: Homogentisate ------> Maleylacetoacetate [ Continue reading >>

Chapter 8: Fuel Nutrient Metabolism

Chapter 8: Fuel Nutrient Metabolism

Chapter 8: Fuel Nutrient Metabolism Presentation by Jill Goode Englett, University of Alabama, and Ellen Brennan, San Antonio College © 2010 Pearson Education, Inc. Metabolism Sum of all chemical reactions in the body’s cells Release of energy Synthesis of biological compounds Never stops Adapts to individual needs and the environment Includes a number of metabolic pathways © 2010 Pearson Education, Inc. Options for Using Fuel Nutrients Temporary Storage Anabolism – building a structural or functional molecule Catabolism – releasing stored energy; end products are CO2, H2O, and energy (ATP and heat) Aerobically – with O2 Anaerobically – without O2 © 2010 Pearson Education, Inc. Most metabolically active organ in the body First organ to metabolize, store, and distribute nutrients after absorption Proteins, carbohydrates, and fats are absorbed as: Amino acids Monosaccharides Glycerol and fatty acids Liver’s Role in Regulating Metabolism © 2010 Pearson Education, Inc. Amino acids, monosaccharides, glycerol and fatty acids in the liver can be Used for energy directly Used to build structural or regulatory compounds Stored Glycogen Triglycerides – transported via VLDLs to adipose tissue Liver’s Role in Regulating Metabolism © 2010 Pearson Education, Inc. Metabolism Allows Some Conversion of Fuel Nutrients Glucose into fat Liver Adipose tissue Amino acids into fat - liver Glycerol and some amino acids into glucose - liver Glucose and fats (with a source of N) into non-essential amino acids - liver © 2010 Pearson Education, Inc. Significance Of These Conversions Composition of the diet is not as immediately important Efficient storage of energy as fat frees us from the need to eat constantly How does thi Continue reading >>

Nutr 251 Exam 2 Review (minus Lipids)

Nutr 251 Exam 2 Review (minus Lipids)

Briefly outline the process of digestion and absorption of beef protein. 2) Stomach-HCL denature proteins, pepsin is activated to further break down proteins to smaller polypeptides 3) Small intestine-90% of digestion of proteins occurs here, pancreatic/enzymes break polypeptides down further to amino acids 4) Absorbed by active transport, travels to the portal vein and then to the liver 4 functions of essential amino acids other than protein synthesis 1) Act as precursors (ex- tryptophan can be converted to serotonin) 2) Used for fuel, but to lesser degree than fatty acids and glucose 3) Converted to fatty acids and put into fat cell storage when energy in is greater than energy out (there is too much protein being converted to fat) 4) Carbon portion can be converted to glucose in a process called gluconeogenesis which happens in starvation Chemical structure of protein vs. complex carbohydrates -A protein is made of long chains of amino acids linked together by peptide bonds -Complex carbohydrates are made of glucose units in straight or branched chains How is the chemical structure of a monosaccharide different from that of an amino acid? 1) Collagen- the framework for bone/teeth structures 2) Regulate fluid balance- R groups are charged and can attract water 6) Hormones (insulin and gastrin are protein hormones) What happens to the ammonia and urea as an end product of this process? Deamination- amino acids are stripped of their nitrogen containing amino groups, first step when amino acids are broken down [Products of deamination are ammonia and a keto acid (the carbon part of the amino acids)] Ammonia combines with CO2 and is excreted as urea How many essential amino acids are in the diet? Describe the sources of amino acids for the "amino acid pool." Why must thi Continue reading >>

Glucogenic Amino Acids | The Biochemistry Questions Site

Glucogenic Amino Acids | The Biochemistry Questions Site

A free Biochemistry Question Bank for premed, medical students and FMG Answer to Biochemistry Question AM-02 about Amino acid Metabolism. Answer: (b) Ketogenic (Since the question only make reference to acetoacetyl CoA, we assume that it is the final product of the catabolism of this amino acid and no glucogenic metabolites are produced.) Amino acids are used for different purposes in our body. Most of the metabolic pool of amino acids is used as building blocks of proteins, and a smaller proportion is used to synthesize specialized nitrogenated molecules as epinephrine and norepinephrine, neurotransmitters and the precursors of purines and pyrimidines. Since amino acids can not be stored in the body for later use, any amino acid not required for immediate biosynthetic needs is deaminated and the carbon skeletonis used as metabolic fuel (10-20 % in normal conditions) or converted into fatty acids via acetyl CoA. The main products of the catabolism of the carbon skeleton of the amino acids are pyruvate, oxalacetate, a-ketoglutarate, succinyl CoA, fumarate, acetyl CoA and acetoacetyl CoA. When carbohydrates are not available (starvation, fasting) -or cannot be used properly, as in diabetes mellitus, amino acids can become a primary source of energy by oxidation of their carbon skeleton, but also by becoming an important source of glucose for those tissues that only can use this sugar as metabolic fuel. The formation of glucose from amino acids (gluconeogenesis) in liver and kidney is intensified during starvation and this process becomes the most important source of glucose for the brain, RBC and other tissues. Amino acids in skeletal proteins can be used, in a situation of prolonged starvation as an emergency energy store that can yield 25000 kcal. Amino acids can be cl Continue reading >>

Ch432_lec_23jan

Ch432_lec_23jan

CATABOLISM OF AMINO ACID CARBON SKELETONS Let's Begin by reviewing the amino acid carbon skeleton catabolismwe covered last semester. The catabolic breakdown of most of the amino acids is summarizedin the Main Routes of Amino Acid Catabolism diagram inyour packet. A couple of overview comments. First, quite a numberof aa catabolic pathways have irreversible steps, as symbolizedby the heavy arrows in the diagram. These amino acids will beessential (that is must be provided by the diet). Generallywe find that amino acids are essential in mammals (cannot be synthesized)if they are only needed to make protein. Non-essential aa's, suchas serine, are biosynthesized by us because they have importantroles in intermediary metabolism, not because they are neededto make protein. Second, amino acids can be categorized as beingglucogenic (can be used in Gluconeogenesis) or ketogenic(cannot be used in Gluconeogenesis). Most aa's can be at leastpartially used in glucose synthesis. But ilu is only partiallyglucogenic (note some goes directly to acetyl-CoA), while leuand lys are fully ketogenic. We will begin by looking at the catabolism of amino acids bygroups: 3-C (feed into pyruvate), 4-C (feed into oxalacetate),and 5-C (feed into glutamate). 3-C aa's: Ser and alaare converted in single step processes to pyruvate. Cysis converted after first oxidizing and removing sulfur as sulfate. 4-C aa's: Asn is hydrolyzedin one step to aspartate, which in turn is transaminatedin one step to oxalacetate. Threonine feeds into the TCAcycle through succinyl-CoA instead of oxalacetate. Thr is firstdeaminated via a dehydratase as seen earlier, then decarboxylatedby Pyruvate DH Complex to give propionyl-CoA, which is then transformedvia a series of steps to give succinyl-CoA. Propionyl-CoA metabolism: Continue reading >>

More in ketosis