No abstract

The single, highly stable form of mouse submandibular gland nerve growth factor (NGF), prepared as described by Young eta. [(1978) Biochemistry 17, 1490-1498] is a protease of restricted specificity that can convert plasminogen to plasmin. In the absence of plasminogen, NGF is not fibrinolytic, nor does it hydrolyze casein at a measurable rate. Treatment of NGF with diisopropyl fluorophosphate inhibits its ability to activate plasminogen as well as its capacity to hydrolyze certain synthetic argnine esters. These results indicate that NGF is a member of the class of serine proteases. Since

Chlamydia trachomatis grown in the yolk sac of embryonated eggs was purified by centrifugation on continuous isopycnic Renografin density gradients. A band of chlamydial particles with a buoyant density of 1.20 contained 70% of the starting particles, and electron microscopy revealed the virtual absence of contaminating egg material. Centrifugation on Renografin gradients caused only a moderate decrease in infectivity. For large-scale purification, infected yolk sac was centrifuged through Renografin solutions, resulting in greater than 60% recovery of starting chlamydial particles, but less than 1% recovery of the dry weight and protein.

Chlamydia trachomatis grown in the yolk sac of embryonated eggs was purified by centrifugation on continuous isopycnic Renografin density gradients. A band of chlamydial particles with a buoyant density of 1.20 contained 70% of the starting particles, and electron microscopy revealed the virtual absence of contaminating egg material. Centrifugation on Renografin gradients caused only a moderate decrease in infectivity. For large-scale purification, infected yolk sac was centrifuged through Renografin solutions, resulting in greater than 60% recovery of starting chlamydial particles, but less than 1% recovery of the dry weight and protein.