[New substrates for enteropeptidase. I. Biologically active hepta-nonapeptides].
Enteropeptidase (enterokinase, EC 3.4.21.9) hydrolyzes peptide bonds formed by carboxyl groups of Lys or Arg residue provided that less than four negatively charged amino acid residues are in positions P2-P5 of its substrate. We determined the kinetic parameters of three substrates of this type: human angiotensin II (AT) (DR decreases VYIHPF) and the Hb(2-8) (LTAEEK decreases A) and Hb(1-9) (MLTAEEK decreases AA) peptides of the cattle hemoglobin beta-chain. The Km values for all the substrates (approximately 10(-3) M) were one order of magnitude higher than those of the typical synthetic substrates of enteropeptidase or chimeric proteins with the -DDDDK- full-size linker (Km approximately 10(-4) M). The kcat values for AT and Hb(2-8) were also close and low (approximately 30 min-1). The general hydrolysis efficiency of such substrates is no more than 1% of the corresponding value for the typical peptide and protein substrates of the enteropeptidase. However, the elongation of Hb(2-8) peptide by one amino acid residue from its N- or C-terminus results in a dramatic increase in the catalytic efficiency of the hydrolysis: the kcat value for Hb(1-9) is 1510 min-1, which means that it is hydrolyzed only three times less effective than the chimeric protein with the full-size linker.
Likhareva
V V
VV
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, GSP Moscow, 117997 Russia.
Vas'kovskiĭ
B V
BV
Shepel'
N E
NE
Garanin
S K
SK
Mikhaĭlova
A G
AG
Rumsh
L D
LD
D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D004765:Enteropeptidase / Q000378:metabolism*; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014362:Trypsinogen / Q000378:metabolism
D006454:Hemoglobins; D010446:Peptide Fragments; D010455:Peptides; D000804:Angiotensin II; D014362:Trypsinogen; D004765:Enteropeptidase
Novye substraty énteropeptidazy. I. Biologicheski aktivnye gepta-nonapeptidy.