Alanyl dipeptide

P-Alanine, a metabolite of cysteine (Figure 34-9), is present in coenzyme A and as P-alanyl dipeptides, principally carnosine (see below). Mammalian tissues form P-alanine from cytosine (Figure 34-9), carnosine, and anserine (Figure 31-2). Mammalian tissues transami-nate P-alanine, forming malonate semialdehyde. Body fluid and tissue levels of P-alanine, taurine, and... 

The P-alanyl dipeptides carnosine and anserine (A -methylcarnosine) (Figure 31-2) activate myosin ATPase, chelate copper, and enhance copper uptake. P-Alanyl-imidazole buffers the pH of anaerobically contracting skeletal muscle. Biosynthesis of carnosine is catalyzed by carnosine synthetase in a two-stage reaction that involves initial formation of an enzyme-bound acyl-adenylate of P-alanine and subsequent transfer of the P-alanyl moiety to L-histidine. 

Williams, D. E. 1990. Alanyl Dipeptide Potential-Derived Net Atomic Charges and Bond Dipoles, and Their Variation with Molecular Conformation. Biopolymers 29, 1367-1386. 

D. E. Williams, Biopolymers, 29, 1367 (1990). Alanyl Dipeptide Potential-Derived Net... 

Fig. 2.6 Schematic representation of the S subsites of the p2 active site of the yeast 20S proteasome as structural model for the design of maleoyl-y -alanyl-dipeptide aldehydes as a new type selective heterobifunctional inhibitors.

Table 2.3 Inhibition of the PGPH, trypsin- and chymotrypsin-like activities of yeast 20S proteasome by maleoyl- S-alanyl-dipeptide aldehydes (/C50, pM)...

Malein imide 1400 Maleoyl-alanyl-dipeptide aldehyde 404 Malva parvijlora 483 Mammary adenocarcinoma... 

Vo, T. U., McGown, L. B. (2004). Selectivity of quadruplex DNA stationary phases toward amino acids in homodipeptides and alanyl dipeptides. Electrophoresis 25, 1230-1236. 

The third amino acid is involved in forming cross-links by transpeptidation and it is notable that though this amino-acyl residue is somewhat variable, the terminal D-alanyl group that is eliminated is not. Apart fi-om obscure groups, such as the methanogens, all bacteria seem to use a terminal D-alanyl dipeptide. 

D. E. Williams, J. Comput. Chem., 9, 745 (1988). Representation of the Molecular Electrostatic Potential by Atomic Multipole and Bond Dipole Models. D. E. Williams, Biopolymers, 29, 1367 (1990). Alanyl Dipeptide Potential-Derived Net Atmnic Charges and Bond Dipoles, and Their Variation with Molecular Conformation. 

Dunkel A., Hofmann T. Sensory-directed identification of fS-alanyl dipeptides as contributors to the thick-sour and white-meaty orosen-sation induced by chicken broth. Journal of Agricultural and Food Chemistry, 57 9867-9877 (2009). 

N. Gresh, G. Tiraboschi, and D. R. Salahub, Biopolymers, 45(6), 405-425 (1998). Conformational Properties of a Model Alanyl Dipeptide and of Alanine-Derived Ohgopeptides Effects of Solvation in Water and in Organic Solvents - A Combined SIBFA/Continuum Reaction Field, ab Initio Self-Consistent Field, and Density Functional Theory Investigation. 

---