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Ketogenic amino adds

Carbohydrates are introduced into the Krebs cycle at the point where pyruvate dehydrogenase catalyzes conversion of pyruvate to acetyl-Co A with the concomitant reduction of NAD. Citrate synthase catalyzes introduction of the 2-carbon unit of acetyl-CoA into the Krebs cycle. Pyruvate can arise from glucose, fructose, lactate, alanine, and glycerol. Acetyl-CcjAcan arise from pyruvate, as well as from fatty acids. Oxidation of fatty acids results in production of acetyl-Co A, which enters the Krebs cycle at the point catalyzed by citrate synthase. Breakdown of ketogenic amino adds also results in the production of acctyl-CoA, which enters the Krebs cycle at this point. Citrate and malate occur in high cor centrations in certain fruits and vegetables. These chemicals directly enter the Krebs cycle at the indicated points. [Pg.228]

Leucine and lysine are purely ketogenic amino adds. The catabolism of these amino acids does not yield intermediates of the Krebs cycle. It does not yield pyruvate. It does not produce compoimds that can result in the net synthesis of glucose. Leucine catabolism results in the production of a molecule of acetyl-CoA and a molecule of acetoacetate lysine breakdown produces acetoacetyl-CoA. [Pg.436]

Figure 26-8 Metabolic relations among intermediates of carbohydrate, fat, and protein metabolism. Note that acetyi-CoA is produced from both carbohydrate and fat,The glucogenic amino acids, derived from protein metabolism, enter glycolytic paths as a-lceto acids. Ketogenic amino adds enter as acetyl-CoA. Figure 26-8 Metabolic relations among intermediates of carbohydrate, fat, and protein metabolism. Note that acetyi-CoA is produced from both carbohydrate and fat,The glucogenic amino acids, derived from protein metabolism, enter glycolytic paths as a-lceto acids. Ketogenic amino adds enter as acetyl-CoA.
Isoleucine is both ketogenic and glucogenic, because its metab olism yields acetyl CoA and propionyl CoA. The first three steps in the metabolism of isoleucine are virtually identical to the initial steps in the degradation of the other branched-chain amino adds, valine and leucine (see Figure 20.10). [Pg.264]

The amino adds can be classified according to whether they are glucogenic or ketogenic. This classification is based on the pathways of catabolism followed by... [Pg.435]

Amino adds also can give molecules of hexoses and this glucogenic property is particularly evident with those amino adds which enter the cycle of priming reactions at the level of a-ketog utaiic add and pyruvic add. Amino adds which enter at the level of acetoacetate can also, g erally, follow the same path, but they tend to bring about an accumulation of acetoacetic add and other ketone bodies . They are therefore termed ketogenic . [Pg.241]

Norvaline is strongly ketogenic (79). The L-form is attacked by L-amino acid oxidase (77) and the D-form by D-amino add oxidase (1S9). Its susceptibility to transamination has not been reported. Hassan and Greenberg (1S6) demonstrated that it is readily oxidized to COt in the intact animal. More of this amino add is excreted unchanged in the urine than is leudne. [Pg.110]

L-Lysine is an indispensable dibasic AA (L-2,6-diaminohexanoic add) required for hiunan growth and for maintaining nitrogen balance in adults. Lysine cannot be synthesized by the body, and therefore must be supplied through diet. Lysine and threonine are the only essential AAs whose amino gronps do not contiibnte to the total body amino pool because they do not participate in transamination reactions. Metabolites of lysine catabolism enter the TCA cycle only at the acetyl-CoA site, and therefore cannot serve as substrates for glucose synthesis. Consequently, lysine functions strictly as a ketogenic AA. ... [Pg.294]


See other pages where Ketogenic amino adds is mentioned: [Pg.246]    [Pg.435]    [Pg.228]    [Pg.421]    [Pg.527]    [Pg.345]    [Pg.246]    [Pg.435]    [Pg.228]    [Pg.421]    [Pg.527]    [Pg.345]    [Pg.241]    [Pg.272]    [Pg.423]    [Pg.436]    [Pg.436]    [Pg.445]    [Pg.282]    [Pg.34]   
See also in sourсe #XX -- [ Pg.23 , Pg.435 ]




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Amino adds

Ketogenic

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