SUMMARY: The cell-wall-bound proteinase from subsp. NCDO 151 was purified to homogeneity by anion-exchange and hydrophobic-interaction chromatography, chromatofocusing and gelfiltration. The purification resulted in a 600-700-fold increase in specific activity of the proteinase and the final yield was approximately 20%. Upon chromatofocusing, two proteolytically active components, termed pro 135 and pro110, were detected. pro135 had an isoelectric point of 4·2. It had an of about 300000 as determined by gelfiltration and 135000 as judged by SDS-PAGE, indicating that it may exist as a dimer in its native state, pro110 had an isoelectric point of 4·4, and an of about 150000 as determined by gel-filtration and 110000 as judged by SDS-PAGE. pro110 appears to be a degradation product of pro135 as they have the same N-terminal amino acid sequence. The first N-terminal amino acid was ambiguous for both components, whereas the sequence from the second to the ninth amino acid was Ala-Lys-Ala-Asn-Ser-Met-Ala-Asn. This is identical to the corresponding sequence of the lactococcal cell-wall-bound proteinases. Although the proteinase was a little smaller than the lactococcal proteinase, their purification characteristics were very similar, suggesting that these proteinases are related.


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