Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:3.4.21.4 (
trypsin
)
42,187
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The active fragment with Lys at the reactive site of mung bean trypsin inhibitor (MBILF) is composed of two peptide chains, A1 of 26 residues and A2 of 9 residues linked via two disulfide bonds. In the present study, a peptide of 22 residue comprising the sequence of chain A1 from position 3 to 24 was synthesized by the solid-phase method. This synthetic peptide with six Cys residues contains a reactive site at position Lys11I-Ser12I (I denotes an inhibitor residue). Air oxidation and HPLC purification resulted in two antitrypsin active components,
SPC1
and SPC2. Neither
SPC1
nor SPC2 can stoichiometrically inhibit
trypsin
. The Ki values of
SPC1
and SPC2 are 1.2 x 10(-7) and 4.0 x 10(-8) M, respectively. The complexes of
SPC1
and SPC2 with bovine
beta-trypsin
(BTRY) were crystallized by ammonium sulphate precipitation at pH 6.4 and 6.0, respectively. The two crystals have the same crystal form with space group P2(1)2(1)2(1) and cell dimension of a = 63.2(2) A, b = 63.5(6) A, and c = 69.8(4) A. The crystal structure of one complex,
SPC1
-BTRY, was determined and refined at 2.2 A resolution to a final R-value of 19.2%. From the resulting electron density map, 9 residues of
SPC1
, from position 9I to 17I, were identified clearly and three-dimension atomic model of the 9-residue reactive loop formed by a disulfide bridge, Cys9I-Cys17I, was built. No electron density corresponding to the other 13 residues was observed in the present map.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Studies on an artificial trypsin inhibitor peptide derived from the mung bean trypsin inhibitor: chemical synthesis, refolding, and crystallographic analysis of its complex with trypsin. 779 76
The active
trypsin
inhibiting component,
SPC1
, was obtained during the synthesis of a 22-residue peptide with three disulfide bridges according to the mimic mung bean Bowman-Birk type inhibitor. The K(i) value of
SPC1
is 1.2x10(-7) M. In order to determine the topological structure of
SPC1
, X-ray diffraction studies were carried out on the complex of
SPC1
with bovine
beta-trypsin
. Only the binding loop of
SPC1
resolved at 2.2 A resolution due to conformational flexibility of the other residues [1]. The amino acid sequence was re-determined and electrospray mass spectroscopy was also performed to ensure that no cleaving occurred on
SPC1
and the primary sequence of
SPC1
is correct. Because the protein is more rigid in nonaqueous medium as has been proved by others [2], we treated the complex of
SPC1
with neat cyclohexane and then subjected it to X-ray diffraction analysis, and the result showed that all the 22 residues of
SPC1
were located in the electron density map. So the topological structure of
SPC1
has been determined, suggesting that crystal treatment with cyclohexane may be used as a method to determine the conformation of the disordered regions in protein crystal structures.
...
PMID:X-Ray study on an artificial mung bean inhibitor complex with bovine beta-trypsin in neat cyclohexane. 1125 12
