Crystallization of a soluble form of the Kexlp serine carboxypeptidase from Saccharomyces cerevisiae

A soluble form of the killer factor and prohormone‐processing carboxypeptidase, “KexlΔp,” from Saccharomyces cerevisiae , has been crystallized in 17–22% poly (ethylene glycol) methyl ether (average M r = 5, 000), 100 mM ammonium acetate, 5% glycerol, pH 6.5, at 20 °C. A native data set (2.8 Å resolution) and four derivative data sets (3.0–3.2 Å resolution) were collected at the Photon Factory (λ = 1.0 Å). The crystals belong to space group P2 1 2 1 2 1 with a = 56.6 Å, b = 84.0 Å, c= 111.8 Å. Freezing a KexlΔp crystal has facilitated the collection of a 2.4‐Å data set using a rotating anode source (λ = 1.5418 Å). Molecular replacement models have been built based on the structures of wheat serine carboxypeptidase (CPDW‐II; Liao DI et al., 1992, Biochemistry 31 :9796–9812) and yeast carboxypeptidase Y (CPD‐Y; Endrizzi JA, Breddam K, Remington SJ, 1994, Biochemistry 33 :11106–11120).