Substitution of lysine for arginine at position 199 of a hypoxanthine phosphoribosyltransferase interferes with binding of the primary substrate to the active site.

Craig SP, Focia PJ, Fletterick RJ. Substitution of lysine for arginine at position 199 of a hypoxanthine phosphoribosyltransferase interferes with binding of the primary substrate to the active site. Biochim Biophys Acta. 1997 Apr 25; 1339(1):1-3.