| Popis: |
Chromatographically homogeneous egg-white lysozyme and crystalline α-chymotrypsin were irradiated in a Cs137 source with γ-rays, and the resulting samples were subjected to amino acid analyses, chromatographic examination, and deuterium exchange measurements. After a 10.7 Mrad dose3 one residue each of serine and tryptophan are lost per mole of α-chymotrypsin while in lysozyme, after a 26.6 Mrad dose 3 , no significant loss in any amino acid residue is observed. From irradiated α-chymotrypsin only one discrete active component can be demonstrated chromatographically. Chromatographic examination of the phosphate soluble material in irradiated lysozyme reveals five active and one inactive components. In α-chymotrypsin hard-to-exchange-amide (peptide) hydrogens are lost at about the same rate as enzymic activity as a function of radiation dose. In lysozyme, irradiation disrupts conformation so that hard-to-exchange-amide (peptide) hydrogens are lost at least twice as rapidly as enzymic activity. These results indicate that enzymic activity in α-chymotrypsin is closely dependent on native molecular conformation whereas only about half the native conformation of lysozyme is essential to enzymic activity. |
