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DNA photolyase from Escherichia coli (M(r) 54,000) consists of a polypeptide
chain of 471 amino acids and the non-covalently bound cofactors
methenyltetrahydrofolate (MTHF) and flavin adenine dinucleotide (FADH2). Two
crystal forms of the enzyme were obtained; both have symmetry of space group P1.
Form I has the unit cell dimensions a = 89.4 A, b = 97.3 A, c = 62.1 A, alpha =
108.3 degrees, beta = 97.4 degrees and gamma = 90.0 degrees. Diffraction from
this form extends beyond 3 A resolution, but the crystals are
radiation-sensitive and difficult to reproduce. Form II has the unit cell
dimensions a = 62.6 A, b = 72.2 A, c = 58.5 A, alpha = 99.1 degrees, beta =
101.5 degrees and gamma = 72.0 degrees; most likely, the unit cell contains two
molecules. High diffraction quality and reproducibility make form II suitable
for structure analysis.
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