Kinetics of precursor cleavage at the dibasic sites

Abstract

The presence in the PP P 1 position relative to the LysArg doublet of either Phe, Tyr or Trp residues affects only pro-OT/Np(7^15) flexibility. This has a measurable effect on the dynamics of the peptide. Since the same modifications have a major influence on the K m and V max values of the peptide cleavage, these kinetic parameters should depend on the peptide substrate motions. Therefore, the primary kinetic contribution of substrate cleavage should arise from substrate dynamics rather than from the enzyme. ß

Processing of peptide and hormone precursors at the dibasic cleavage sites

“…6). [64] Prosomatostatin and its derivatives Somatostatin is a 14-amino acid peptide widely distributed in the central nervous system and peripheral tissues in which it has diverse physiological actions. This peptide acts as a neuromodulator or a neurotransmitter in the central nervous system, as a regulatory hormone in the gastrointestinal tract and pancreas and as a release inhibitor of growth hormone and thyroid stimulating hormone in the pituitary [76].…”

“…Since those OT/Np(7-15) peptide analogs were shown to be characterized by the same conformation, the dynamics of substrates must therefore play a role in modulating their proteolysis. So, the plasticity and peptide motions of OT/ Np(7-15) peptides, bearing Phe, Tyr, and Trp amino acid residues at the P 0 1 position, were evaluated by measuring the fluorescence properties of these aromatic residues [64]. As shown in Fig.…”

“…The role of the substrate dynamics in limiting the proteolysis of precursors [64,65] may explain the preference of some amino acid residues at specific subsites [25,46,66,67]. For example, based on the data obtained for both the occurrence frequency of amino acid sequences flanking 352 dibasic moieties and the processing of the OT/Np(7-15) substrate bearing various amino acid residues at the P 0 1 site, we observed that most amino acid residues, occupying the P 0 1 position in the precursor cleavage sites, are tolerated [46].…”

“…4 Fluorescence decay time distribution of Trp, Tyr and Phe residues inserted in the OT/ Np(7-15) peptide (W 13 , Y 13 , F 13 ), as a function of temperature. The free residues (W, Y, F) are characterized by a single population [64] histidine residue at position P6 restricts the cleavage of pro-a4 by furin to acidic compartments. Finally, one of the striking features of proprotein processing is that in vivo cleavage occurs preferentially at LysArg and ArgArg doublets and more seldom at ArgLys and LysLys [26,43].…”

Mammalian Peptide Hormones: Biosynthesis and Inhibition

“…Later, this group showed that introduction of a b-turn breaker into the proposed turn region abolishes the enzyme-substrate interaction [242]. Moreover, they state that the flexibility of the peptide substrate is necessary for the interaction [242,245].…”