States of amino acid residues in proteins

摘要: Abstract A new coupling reagent, diazonium- i -H-tetrazole, for spectrophorometric determination of histidine residues in proteins was explored and applied to several proteins. The reagent has the following characteristics advantageous is superior common diazonium compounds. (a) Histidinebisazo- which reaction product be determined spectrophotometrically, a strong absorption band at 480 mμ, while tyrosinebisazo- -H-tetrazole weaker considerably longer wavelength, 550 mμ. (b) coloration due formation biazohistidine proceeds completion before bis tyrosine residues. (c) does not afford colored by-products during its reactions with amino acids or alkaline pH, so that one can use high concentration necessary determine end point coloration. Because these characteristics, molar content simply by photometry mμ mixtures protein reagent. reacts uniformly all bacitracin, lysozyme (EC 3.2.1.17), insulin, albumin trypsin 3.4.4.4). On other hand, trypsinogen, chymotrypsinogen α-chymotrypsin 3.4.4.5) proceed two steps, second step higher concentrations bound moles latter were discussed referring data obtained previously reagents.