Inhibits trypsin and chymotrypsin. Optimum pH is 4.5-9.0. High activity is also seen over the range pH 2.0-4.5. Activity decreases with increasing pH above pH 9.0. Optimum temperature is 4-65 degrees Celsius. Activity decreases rapidly at higher temperatures, nearly 40% of activity is retained at 100 degrees Celsius. Monomer. Stored in epidermis and secreted into the hemolymph and cuticle. Not detected in the interior of the epidermis, fat body cells or columnar or goblet cells of the midgut epithelium (at protein level). Present in newly hatched larvae. Strongly expressed in the cuticle of fourth and fifth instar larvae. In epidermis, levels decreased with the increase in age of instars. In cuticle, levels increased with increase in age of instars. Glycosylated.