{"@type": "dcat:Dataset", "accessLevel": "public", "bureauCode": ["009:25"], "contactPoint": {"@type": "vcard:Contact", "fn": "NIH", "hasEmail": "mailto:info@nih.gov"}, "description": "Background\n          Proteorhodopsin (pR) is a light-activated proton pump homologous to bacteriorhodopsin and recently discovered in oceanic \u03b3-proteobacteria. One perplexing difference between these two proteins is the absence in pR of homologues of bR residues Glu-194 and Glu-204. These two residues, along with Arg-82, have been implicated in light-activated fast H+ release to the extracellular medium in bR. It is therefore uncertain that pR carries out its physiological activity using a mechanism that is completely homologous to that of bR.\n        \n        \n          Results\n          A pR purification procedure is described that utilizes Phenylsepharose\u2122 and hydroxylapatite columns and yields 85% (w/w) purity. Through SDS-PAGE of the pure protein, the molecular weight of E.-coli-produced pR was determined to be 36,000, approximately 9,000 more than the 27,000 predicted by the DNA sequence. Post-translational modification of one or more of the cysteine residues accounts for 5 kDa of the weight difference as measured on a cys-less pR mutant. At pH 9.5 and in the presence of octylglucoside and diheptanoylphosphotidylcholine, flash photolysis results in fast H+ release and a 400-nm absorbing (M-like) photoproduct. Both of these occur with a similar rise time (4\u201310 \u03bcs) as reported for monomeric bR in detergent.\n        \n        \n          Conclusions\n          The presence of fast H+ release in pR indicates that either different groups are responsible for fast H+ release in pR and bR (i.e. that the H+ release group is not highly conserved); or, that the H+ release group is conserved and is therefore likely Arg-94 itself in pR (and Arg-82 in bR, correspondingly).", "distribution": [{"@type": "dcat:Distribution", "description": "Visit the original government dataset for complete information, documentation, and data access.", "downloadURL": "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC103662/", "mediaType": "text/html", "title": "Official Government Data Source"}], "identifier": "https://healthdata.gov/api/views/s6uv-yjdf", "issued": "2025-07-14", "keyword": ["nih", "proteorhodopsin", "proton-pump", "light-activation", "bacteriorhodopsin"], "landingPage": "https://healthdata.gov/d/s6uv-yjdf", "modified": "2025-09-06", "programCode": ["009:033"], "publisher": {"@type": "org:Organization", "name": "National Institutes of Health"}, "theme": ["NIH"], "title": "Detection of fast light-activated H"}