Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pyridoxal-5'-phosphate (pyridoxal-P) reacts with lysine residues of the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI) at pH 7.4 and 30 degrees C, forming a Schiff-base which was stabilized by NaBH4 reduction. The interaction of pyridoxal-P and BTCI was accompanied by a difference spectrum presenting a negative peak at 382 nm and a positive peak at 435 nm which was shifted to 325 nm by reduction with NaBH4. The kinetics of interaction indicated that a noncovalent protein-pyridoxal-P complex was formed prior to Schiff-base formation. The number of pyridoxal-P (or pyridoxal) groups incorporated per protein molecule after NaBH4 reduction was determined spectrophotometrically as a function of the reagent/protein molar ratio. A saturation value of about 0.75 pyridoxal-P residues per protein molecule was found for an 80-100 molar excess of reagent over the protein. In the case of pyridoxal, the incorporation of reagent into the protein was much less than that of pyridoxal-P. The results obtained indicate that lysine residues in BTCI (5 per molecule) are in unfavourable environments for binding pyridoxal-P. The trypsin and chymotrypsin inhibitory activities of the pyridoxal-P-treated, NaBH4-reduced BTCI are slightly reduced.
 ...
PMID:Interaction of pyridoxal-5'-phosphate and black-eye pea trypsin and chymotrypsin inhibitor. 667 84

The involvement of adenosine triphosphate (ATP) and carbon monoxide (CO) in the non-nitrergic nonpeptidergic component of high-frequency electrical field stimulation (EFS)-induced nonadrenergic noncholinergic (NANC) relaxation of longitudinal muscle strips from the rat gastric fundus was investigated. Under NANC conditions (1 microM atropine + 5 microM guanethidine), N(G)-nitro-L-arginine methyl ester (L-NAME, 1 mM) slightly reduced the amplitude, but did not affect the area under the curve (AUC) of EFS (13 Hz, 2 min)-induced relaxation of 9,11-dideoxy-9alpha,11alpha-methanoepoxy prostaglandin F(2alpha) (U46619, 0.1 microM)-precontracted strips. With L-NAME (1 mM) plus alpha-chymotrypsin (1 U ml(-1)), the amplitude and the AUC of relaxation were reduced to approximately two-third and one-third of controls, respectively. Pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (100 microM), apamin (0.3 microM), desensitization to ATP, suramin (100 microM), zinc protoporphyrin IX (300 microM) or ferrous haemoglobin (100 microM) did not inhibit the component of relaxation resistant to L-NAME plus alpha-chymotrypsin. L-NAME (1 mM) plus anti-vasoactive intestinal peptide (VIP) serum (1 : 100) reduced the amplitude and the AUC of relaxation to a similar extent as L-NAME (1 mM) plus alpha-chymotrypsin (1 U ml(-1)). Adding apamin (0.1 microM) to L-NAME (1 mM) plus anti-VIP serum (1 : 100) further reduced the amplitude and the AUC of relaxation. These findings suggest that the non-nitrergic nonpeptidergic component of NANC relaxation of the rat gastric fundus induced by high-frequency stimulation is mediated by a neurotransmitter that acts through apamin-sensitive mechanisms, that is neither ATP nor CO.
 ...
PMID:Evidence for an apamin-sensitive, but not purinergic, component in the nonadrenergic noncholinergic relaxation of the rat gastric fundus. 1550 56