Lcj

C H2 COO" Phosphocreatine

FIGURE 22-26 Biosynthesis of creatine and phosphocreatine. Creatine is made from three amino acids: glycine, arginine, and methionine. This pathway shows the versatility of amino acids as precursors of other nitrogenous biomolecules.

bound selenium (Se) atom in the form of selenocysteine (see Fig. 3-8a), which is essential for its activity.

D-Amino Acids Are Found Primarily in Bacteria

Although D-amino acids do not generally occur in proteins, they do serve some special functions in the structure of bacterial cell walls and peptide antibiotics. Bacterial peptidoglycans (see Fig. 20-23) contain both D-alanine and D-glutamate. D-Amino acids arise directly from the l isomers by the action of amino acid racemases, which have pyridoxal phosphate as cofactor (see Fig. 18-6). Amino acid racemization is uniquely important to bacterial metabolism, and enzymes such as

Glutamate

7-glutamyl cysteine synthetase

7-glutamyl cysteine synthetase

7-Glu-Cys glutathione synthetase glutathione synthetase

7-Glu

NH3 O O

I II II

"OOC—CH—CH2 —CH2 —C—N—CH—C—N—CH2 —COO"

Weight Loss Funnel

Weight Loss Funnel

Who Else Wants To Discover The 3 Most Effective Fat Burning Methods The Weight Loss Industry Does NOT Want You To Know About.

Get My Free Ebook


Post a comment