Prokaryotes Proline

Project leading, in R D, 21 619 Prokaryotes, defined, 3 757t Prolene suture, 24 215 Proline... 

Signal sequences vary in structure but usually have a net positive charge within the first 5-8 residues at the N terminus. This region is followed by a "hydro-phobic core" made up of 8-10 residues with a strong tendency toward a helix formation. This sequence is often followed by one or a few proline, glycine, or serine residues and then a sequence AXA that immediately precedes the cleavage site. Here, A is usually alanine in prokaryotes but may also be glycine, serine, or threonine in eukaryotes. Residue X is any amino... 

Prokaryotic cells, definition of 2 Proline (Pro, P) 52s in helices 69 reductases 753, 755 Proline rings, torsion angles 62 Prontosil 473s Proofreading... 

Polysaccharides, 44, 58 Prokaryote Cell, 7 Proline, 439 Promoters, 391 Protamines, 149 Proteans, 151 Protein Biosynthesis, 448 Protein Catabolism, 428 Protein Maturation, 449 Proteins, 262 Purine Metabolism, 379 Purines, 113 Pyridoxine, 229 Pyrimidines, 113 Pyruvate Kinase, 288... 

Flo. 44. Schematic representation of amino acid chains of various types of eukaryotic and prokaryotic cytochromes c. Cytochromes are listed at the left beside the amino terminus of each chain. Figures at the right, by the carboxyl terminus, are rough numbers of amino acids per chain. C, H, M, and P are cysteine, histidine, methionine, and proline, and large dots represent unspecified amino acid residues between cysteines. The chain lengths as represented by horizontal lines are only approximate. Adapted from reference 36. ... 

With this cautionary note in mind, we should note that a related enzyme, prolidase from P. furiosus, has also been reported to be a dicobalt enzyme. In contrast to the aminopeptidases discussed above, prolidase specifically cleaves dipeptides containing a C-terminal proline. Prolidase is present in humans and a variety of bacteria, and appears to be identical to the enzyme previously known as organophosphorus acid anhydrolase, which can hydrolyze and detoxify organophosphorus nerve agents.A function in hydrolyzing peptides, rather than nerve agents that have only been known for a few decades, seems much more probable for these enzymes, which are found in both eukaryotes and prokaryotes. Whether prolidases actually utilize a dinuclear cobalt site in catalysis will require further investigation. 

---