Ultraviolet absorption subunits

Bg, a a and B, a. Molecular weights of 52,000 and 57,000 have been reported for the subunits. The six isomeric forms showed ultraviolet absorption spectra similar to that reported originally by Koshiyama (13) with maxima at 278 nm and at 232-234 and a minimum at 250 nm with shoulders at 253, 258, 265 and 269 (10). 

Muscle phosphorylase b consists of two protein subunits, each of which binds one molecule of pyridoxal phosphate. Optical activity can be demonstrated in the absorption band (near 333 nm) of pyridoxal phosphate by CD measurements, while in ORD spectra this Cotton effect is obscured by the protein (354). As measured by rotation in the ultraviolet region, the pyridoxal phosphate has little effect on the ordered structures of the protein (355). 

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