Transport of proteins into chloroplasts. Partial purification of a thylakoidal processing peptidase involved in plastocyanin biogenesis
Plastocyanin is synthesized in the cytoplasm as a larger precursor and transported across three membranes into the chloroplast thylakoid lumen. Processing to the mature size involves successive cleavages by a stromal and a thylakoidal peptidase. In this report we describe the partial purification an...
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Veröffentlicht in: | The Journal of biological chemistry 1987-12, Vol.262 (34), p.16386-16390 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Plastocyanin is synthesized in the cytoplasm as a larger precursor and transported across three membranes into the chloroplast thylakoid lumen. Processing to the mature size involves successive cleavages by a stromal and a thylakoidal peptidase. In this report we describe the partial purification and characterization of the thylakoidal peptidase involved. The enzyme has been purified 36-fold from Pisum sativum thylakoids after solubilization using Triton X-100. The peptidase processes the plastocyanin import intermediate to the mature size, but no further, and is capable of processing pre-plastocyanin to the mature size but at a lower rate. No detectable activity is displayed against non-chloroplast proteins or precursors of stromal proteins. The enzyme has a pH optimum of 6.5-7 and is activated by chelating agents such as EDTA and EGTA. No inhibitors of the peptidase have been found to date. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)49267-8 |