Open AccessPhysicochemical Properties of T 4 Polynucleotide Kinase
Author(s) -
LILLEHAUG Johan R.
Publication year - 1977
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1977.tb11343.x
Subject(s) - tetramer , oligomer , monomer , chemistry , polynucleotide , circular dichroism , ionic strength , crystallography , amino acid , enzyme , stereochemistry , biochemistry , polymer , polymer chemistry , organic chemistry , aqueous solution
Some physicochemical properties of T 4 polynucleotide kinase (EC 2.7.1.78) have been studied. The enzyme is an oligomer of one polypeptide chain. The molecular weight of the monomer is 33000, as determined from the amino acid analysis. Phenylalanine is the N‐terminal amino acid. Each monomer contains two −SH groups, one exposed and one more buried. Circular dichroic spectra suggest a high content of α‐helical structure, 45 – 55%. Excitation at 280 nm gave a strong emission fluorescence spectrum with a maximum centering at 340 nm. Sedimentation studies suggested the enzymically active form to be a tetramer. High ionic strength (0.1 M KCl), spermine, and the substrates ATP and thymidine 3′‐monophosphate were found to be essential factors in order to stabilize the protein in an oligomeric structure. The association constants for ATP, thymidine 3′‐monphosphate, and P i were determined fluorimetrically to be 7.9 × 10 5 , 4.8 × 10 5 , and 7.2 × 10 2 M −1 respectively.