In an earlier paper (1) the writer described the preparation and isolation of three crystalline acetyl derivatives of pepsin. They were, "100 per cent active" acetyl pepsin in which the 3 or 4 primary amino groups of pepsin had been acetylated with less than 15 per cent change in the specific activity; "60 per cent active" acetyl pepsin whichcontained 6-11 acetyl groups per molecule; and "10 pe...

1. A fragment of human subcomponent C1q was prepared by limited proteolysis with pepsin at 37 degrees C for 20 h, and at pH4.4, followed by gel filtration on Sephadex G-200. This fragment was shown to contain all the collagen-like features known to be present in the intact molecule [Reid (1976) Biochem. J. 155, 5-17]. 2. Circular-dichroism studies showed the presence of positive bands at 230 an...

The results (1) of the experiments with crystalline pepsin isolated from crude pepsin preparations indicated that the material is a pure substance and that the proteolytic activity is a property of the protein molecule itself and is not due to the presence of a separate non-protein impurity. No indication of the presence of a more highly active nonprotein molecule was obtained in the solubility...

A factor present in normal rabbit sera enhanced the neutralization of the infectious complex of poliovirus with the pepsin Fab' fragment of rabbit immunoglobulin G (IgG) antibody but showed no activity for the infectious complex of the same virus with IgG antibody. The factor was associated with IgG, and its activity was inhibited by the pepsin Fab' fragment of normal rabbit IgG. The data sugge...

BACKGROUND Gastro-oesophageal reflux is common in children with cystic fibrosis (CF) and is thought to be associated with pulmonary aspiration of gastric contents. The measurement of pepsin in bronchoalveolar lavage (BAL) fluid has recently been suggested to be a reliable indicator of aspiration. The prevalence of pulmonary aspiration in a group of children with CF was assessed and its associat...