Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Estrone glucuronide conjugates of hen egg white lysozyme were prepared by both the mixed-anhydride and active-ester coupling procedures. Both methods gave good yields of conjugate but the active-ester procedure gave a more diverse range of products consistent with a greater acylating ability. Unreacted lysozyme which was present in all cases was removed by a combination of cation-exchange chromatography on a Pharmacia Mono-S column and hydrophobic-interaction chromatography on an Alkyl Superose column. The conjugate families were more hydrophobic than native lysozyme. The chromatographic behaviour of the reaction mixtures on Mono S columns under non-denaturing conditions was complex as a result of hydrophobic effects and only at pH values above 7.0 did the conjugates elute in the order of their overall charges. At pH values below 6.0 the conjugates, although less charged than lysozyme, eluted last on salt gradients. In contrast when denaturing 7 M urea buffers were used the conjugates eluted in the order of their electrostatic charges and reproducible patterns were obtained which served as an excellent analytical system for lysozyme-steroid glucuronide conjugates. The purified conjugate material from the active-ester reaction gave over 90% inhibition of the lytic activity in the presence of an estrone glucuronide antibody. When used in a homogeneous enzyme immunoassay system the levels of urinary estrone glucuronide encountered in a normal menstrual cycle were easily measured.
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PMID:Use of ion-exchange and hydrophobic-interaction chromatography for the rapid purification of lysozyme-estrone glucuronide conjugates. 789 91

Estrone glucuronide conjugates of hen egg white lysozyme were prepared by the mixed anhydride and active ester coupling procedures. Both methods gave good yields of conjugates, but the active ester procedure gave a more diverse range of products, making it less suitable for preparing conjugates for homogeneous enzyme immunoassay. Conjugation of lysozyme with estrone glucuronide by the mixed anhydride procedure gave one major derivative exclusively acylated at lysine residue 33 whereas conjugation by the active ester method gave six derivatives which were acylated at one or more of lysine residues 33, 97, and 116. None of the lysine residues 1, 13, and 96, or the N-terminal alpha-amino group, were acylated in any of the conjugates isolated. The correlation of the conjugate structures with the protein environments of the amino groups in the crystal structure of lysozyme suggested that the sites of acylation were determined not only by the chemical nature of the acylating reagent but also by the surface accessibility and nucleophilicity of the individual lysine residues.
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PMID:Characterization of lysozyme-estrone glucuronide conjugates. The effect of the coupling reagent on the substitution level and sites of acylation. 1041 68