The isolation and properties of the skin-reactive substance in Aedes aegypti oral secretion

Abstract

The skin-reactive substance present in the oral secretion of Aedes aegypti mosquitos was isolated by gel filtration chromatography and found to be a protein of high molecular weight designated as F-1. Amino acid analysis of the protein revealed relatively high proportions of glycine (34%) and proline (11%). The active fraction contained 9% carbohydrate and less than 1% amino sugar, sialic acid, or phosphorus. A random coil structure was suggested for F-1 on the basis of optical rotation and infrared data. A linear relation was established between the diameter of the immediate skin reaction and the logarithm of the weight of F-1 injected. F-1 was completely inactivated by incubation at pH 2.5. A low molecular weight fraction was separated from inactivated F-1 and its amino acid composition was determined.