Penicillin G was found to inhibit the formation of the d-alanyl-l-alanine cross-linkage in intact cells of Micrococcus luteus. This reaction was approximately 50-fold less susceptible to penicillin than the formation of the d-alanyl-l-lysine cross-linkage in the same organism. The presence of two penicillin-susceptible transpeptidation reactions that function in the incorporation of peptidoglyc...

The amino acid sequence of elastase inhibitor, AFLEI, isolated from Aspergillus flavus was determined by the Edman sequencing procedure of peptides derived from digests utilizing clostripain. A molecular weight of 7,525.8 was observed by TOF-MS. AFLEI contained 68 amino acid residues and has a calculated molecular weight of 7,526.2. The search for amino acid homology with other proteins demonst...

Several novel fluorogenic N-aminoacylnaphthyridine substrates were synthesized in good yield and tested for their ability to detect pathogenic bacteria in agar-based cell culture. Simple 2-N-(β-alanyl)amino-5,7-dialkylnaphthyridine substrates were selectively hydrolysed by β-alanylaminopeptidase expressing bacteria, but were subject to diffusion in the agar medium. Diffusion was reduced in the ...

M icroorganisms such as Escherichia coli live in environments subject to rapid changes in the availability of the carbon and nitrogen compounds necessary to provide energy and building blocks for the synthesis of cell material. Their survival depends on their ability to regulate the expression of genes coding for the enzymes and transport proteins required for growth in the altered environment....

1. The tripeptide glycyl-levo-alanyl-glycine in solution of either one or ten equivalents of alkali does not undergo racemization on standing. 2. The dipeptide levo-alanyl-glycine under the conditions given in (1) does not undergo racemization. 3. In ketopiperazines, levo-alanyl-glycine anhydride and in levo-prolyl-glycine anhydride under the influence of dilute alkalies, racemization takes pla...

The adjuvant activity of 29 kinds of carbohydrate analogs of N-acetylmuramyl-L-alanyl-D-isoglutamine on the induction of delayed-type hypersensitivity to azobenzenearsonate-N-acetyl-L-tyrosine was examined in guinea pigs. It was found that the D-manno- and D-galacto-type muramyldipeptides were as active as the D-gluco-type muramyldipeptide (MDP). The structural requirement of the carbohydrate m...

Vancomycin forms complexes with peptides terminating in d-alanyl-d-alanine that are analogous to the biosynthetic precursors of bacterial mucopeptides. The specificity of complex-formation has been studied by means of many synthetic peptides, prepared by both solid-phase and conventional methods. The following conclusions can be drawn: (a) three amide linkages are required to form a stable comp...

BACKGROUND Glutamine (Gln) may become conditionally indispensable during critical illness. The short-term metabolic effects of enteral versus parenteral Gln supplementation are unknown in this clinical setting. OBJECTIVES We studied metabolic effects of intravenous (i.v.) alanyl-Gln dipeptide (AG) supplementation and enteral (e.n.) AG supplementation on plasma Gln concentration, antioxidant s...