title: The state of the single tryptophyl of the black-eyed pea trypsin and chymotrypsin inhibitor by charge transfer with N-methylnicotinamide chloride.
abstract: The single tryptophan residue of the black-eyed pea trypsin and chymotrypsin inhibitor was found to be sufficiently exposed to bind N-methylnicotinamide chloride and give rise to a characteristic charge-transfer absorption spectrum. At pH 7.0, ionic strength of 1M and 25 degrees C, an apparent association constant K = 3.19 +/- 0.07 M-1 and a molar extinction coefficient epsilon = 1240 +/- 18 M-1 cm-1 (at 350 nm) were obtained for the charge-transfer complex. The values of these parameters were also estimated for other wavelengths over the 330-420 nm range. The association constant showed a negligible dependence on the wavelength.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002918:Chymotrypsin / Q000037:antagonists & inhibitors; D009536:Niacinamide / Q000031:analogs & derivatives; D011189:Potassium Chloride; D012639:Seeds; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D014361:Trypsin Inhibitors; D014364:Tryptophan
chemical_list: D014361:Trypsin Inhibitors; D009536:Niacinamide; D011189:Potassium Chloride; D014364:Tryptophan; D002918:Chymotrypsin; C008472:N-methylnicotinamide