Peptide from bacteria

There is only a small selection of nonprotein amino acids that contain carbonyl groups in the form of ketone, aldehyde, and carboxylic acid moieties, as part of the side chain. The examples given in Table 6 are components of nonribosomal peptides isolated from bacteria or fungi and siderophores from bacteria. The biosynthesis of these amino acids is not clear however, some of the amino acids with carboxylic acid side chains may be traced back to the L-a-amino acids aspartic acid and glutamic acid. 

Jason Kindrachuk is a postdoctoral fellow at the University of British Columbia (UBC) in the laboratory of Professor R. E. W. Hancock. Jason received his Ph.D. from the University of Saskatchewan in 2007 where his research focused on host and pathogen sensory systems. During his study he specially focused on TLR-9 receptor—ligand interactions and the interactions between host defense peptides and the PhoPQ two-component sensory system of Salmonella typhimurium. In 2008 Jason received the Canadian Cystic Fibrosis Foundation Kin Canada Fellowship for his research in the area of alternative therapies for treatment of antibiotic- and multidrug-resistant bacteria. Currently his research is focused on the investigation of structure-activity relationships amongst natural and synthetic host defense peptides from the perspective of associated immunomodulatory activities and as well as vaccine formulation strategies. 

The key feature which draws attention to these peptides in respect to food applications is their ability to inhibit undesirable organisms, either spoilage or pathogenic organisms. Although the peptides from eukaryotic sources appear far-removed from immediate application in foods, it is important to study their mechanism(s) of action in relation to those of lactic acid bacteria to better understand commonalities in structure-function Such commonalities may serve as a base from which to initiate molecular... 

A natural (1 counterpart has not yet been obtained for every proteinogenic a-amino acid (Table 1.5.1). /I-A la 1 and (R)- or (S)-fi- Aib 2 seem to be present in all kingdoms, with no obvious preferences. Selected /l-amino acids, for example /1-Lys 4, have been found only within one kingdom (i.e. bacteria), although they might be quite common there. Accordingly, the various natural products that contain /1-Lys substructures have been isolated exclusively from bacteria. On the other hand, alkaloids and peptides linked to / -Phe 8 have been obtained from bacteria, plants, and fungi, whereas the free /l-amino acid / -Phe 8 has not yet been isolated from natural sources. 

Smacchi, E. and Gobbetti, M. 1998. Peptides from several Italian cheeses inhibitory to proteolytic enzymes of lactic acid bacteria, Pseudomonas fluorescens ATCC 948 and to the angiotensin I-converting enzyme. Enzyme Microb. Technol. 22, 687-694. 

The dioxygen reduction site of the key respiratory enzyme, cytochrome c oxidase [E.C. 1.9.3.1], is a bimetallic catalytic center comprised of a heme iron adjacent to a Type 2 mononuclear copper center (see Cytochrome Oxidase). The recent solution of the X-ray crystal structure of this enzyme revealed an entirely unanticipated covalent modification of the protein structure, a cross-link between a histidine and tyrosine side chain (23) within the active site (Figure 2)." This extraordinary posttranslational modification has been confirmed by peptide mapping and mass spectrometry, and has been detected as a conserved element in cytochrome c oxidases isolated from organisms ranging from bacteria to cows. The role of the cross-linked structure in the function of cytochrome c oxidase is still controversial." " ... 

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