FTIR STUDIES OF ORGANOMETALCARBONYL-TAGGED ENZYMES

Attachment of organometaltricarbonyl tags to enzymes is revealed by ch anges in the vibrational modes of the carbonyl groups. Shoulders on nu (sym)(CO) and nu(asym)(CO) bands in the FTIR spectrum of an organometa llic tag derived from ,5-eta)-2,4-cyclohexadien-1-yl}pyridinium]iron(1 +) hexafluorophosphate(1-)were detected on binding to enzymes (alpha-c hymotrypsin, ribonuclease A, alkaline phosphatase and a triacylglycero l lipase). By comparison with tagging reactions between the tricarbony liron moiety and model compounds, the new spectral features were attri buted to an iron complex covalently bonded to the NH2 groups of the am ino acid residues of the enzymes. FTIR spectroscopy was used to monito r deprotonation of tagged amino groups on the enzyme surface. Interact ions between the organometalcarbonyl tag and other side-chain groups o f the amino acid residues were also investigated. (C) 1997 Elsevier Sc ience B.V.