Role of Lysine in catalysing Ester Hydrolysis
RECENTLY, Gero and Withrow1 have cited the catalysis of alkaline triglyceride hydrolysis by lysine as a chemical model of a biological reaction. They postulated a bifunctional2 attack by lysine upon the carbonyl O and C of the ester linkage as the mechanism of this hydrolysis.
Chemical Model of a Biological Reaction
WE were searching for a model of an enzymatic reaction in the hope that the relatively simple chemistry of the model reaction might throw some light on the enzyme reaction itself. In particular, we were interested in finding a model which would duplicate some of the properties of lipases, notably their ability to catalyse the hydrolysis of lipids and the characteristic pH dependence of lipolytic activity which reaches a maximum near pH 8.5 with most lipases, and one just below pH 7 with some. Lipases being proteins, the model would have to be restricted to the functional groups available in proteins. The high potency of lipases, despite this restriction, together with the well-known chemical mechanism of ester hydrolysis, made us suspect that bifunctional catalysis1 might play a decisive part.
The Inca Occupation of the South Coast of Peru
like the others, however; it forks into several nearly parallel ravines of which the largest are Huayuri, Rio Grande-Palpa, Ingenio (called Collao in ancient times), Nasca proper (the ancient Caxamarca), Taruga, and Poroma. Due to peculiarities of the local topography, the irrigated areas in Ica and the ravines of Nasca are located inland, at the foot of the mountains, rather than at the mouths of the rivers as is more usual in Peruvian coastal valleys. No sharp natural or cultural boundary separates the valley of Chincha from the valleys of Cafiete (ancient Huarco and Runahuana), Asia, and Mala, the next valleys going up the coast to the northwest. At the other end of the area we are considering, however, there is a sharp break; beyond Yauca the Andean foothills reach out to the sea, natural conditions are quite different, and there are important differences in the archaeological picture as well. The historical sources which mention the south coast are not particularly helpful, except in so far as they provide us with a few dates. To begin with, no chronicler gives an explicit account of the political organization of the south coast at the time it came into contact with the Incas. It can, perhaps, be inferred from Cabello Balboa's statements about common policy toward the Inca invaders that there was some sort of political connection between the valleys of Mala, Cafiete, and Chincha, but the connection need have been no more than a temporary military alliance. Cabello makes no mention at all of Pisco. The valleys of Ica, Nasca, and 125