Physical Properties and Subunit Structure of Xanthosine 5′-Phosphate Aminase

摘要: Abstract Xanthosine 5'-phosphate aminase (xanthosine 5'-phosphate:ammonia ligase (AMP), EC 6.3.4.1) was purified from Escherichia coli B-96. The purity of the enzyme preparation established by its behavior in disc gel electrophoresis, ultracentrifugation, and filtration. extinction coefficient (E1%280) determined to be 11.2 cm-1 with use analytical ultracentrifuge as a differential refractometer. diffusion (D020,w) 5.09 x 10-7 cm2 s-1 obtained measurement free ultracentrifuge. Differential sedimentation equilibrium provided value 0.739 ml per g for partial specific volume (v). (s020,w) estimated 5.91 10-13 s. molecular weight measurements 126,000 ± 4,000. Disc electrophoresis sodium dodecyl sulfate, guanidine hydrochloride, NH2-terminal analysis indicated that xanthosine is dimer composed identical subunits. subunit 63,000 3,000. Possible dimensions consistent hydrodynamic properties are discussed.