vorD VORD_PYRFU 2-oxoisovalerate oxidoreductase delta chain Ketoisovalerate oxidoreductase subunit vorD 105 MNTLFGKTKEEAKPIVLKSVDEYPEAPISLGTTLVNPTGDWRTFKPVVNEEKCVKCYICWKYCPEPAIYIKPDGYVAIDYDYCKGCGICANECPTKAITMIKEEK 2-oxoisovalerate ferredoxin reductase subunit delta PF0970