Hepatitis B antigen (HB Ag) has been purified from serum by pepsin digestion and equilibrium sedimentation. The sedimentation coefficient, density, particle size, and electrophoretic mobility have been determined before and after purification and found to be unaltered. In addition, the diffusion constant and molecular weight of purified HB Ag have been documented. Because the biophysical charac...

The study of protein glycosylation has lagged far behind the progress of current proteomics because of the enormous complexity, wide dynamic range distribution and low stoichiometric modification of glycoprotein. Solid phase extraction of tryptic N-glycopeptides by hydrazide chemistry is becoming a popular protocol for the analysis of N-glycoproteome. However, in silico digestion of proteins in...

Allen, Adrian, and Gunnar Flemström. Gastroduodenal mucus bicarbonate barrier: protection against acid and pepsin. Am J Physiol Cell Physiol 288: C1–C19, 2005; doi:10.1152/ajpcell.00102.2004.—Secretion of bicarbonate into the adherent layer of mucus gel creates a pH gradient with a near-neutral pH at the epithelial surfaces in stomach and duodenum, providing the first line of mucosal protection...

The avian sarcoma/leukemia virus protease (PR), purified from avian myeloblastosis virus has a native molecular mass of 26 kDa, suggesting a dimer structure. The enzymatic activity of PR has been characterized using synthetic peptide substrates. PR is most active at pH 5.5, 35 degrees C and 2-3 M NaCl. Under these conditions PR cleaves decapeptides which are resistant in low ionic strength. Thi...

An in vitro method for estimating food iron availability is described. The method involves simulated gastrointestinal digestion followed by measurement of soluble, low molecular weight iron. Mixtures of foods (meals) were homogenized and exposed to pepsin at pH 2. Dialysis was used to adjust the pH to intestinal levels and digestion was continued after the addition of pancreatin and bile salts....

The hypophyseal substance-the synergic factor-which gives increased gonadotropic effects when combined with prolan has been shown to itself possess a definite though slight gonadotropic activity. It produces transitory follicular enlargement within 24-48 hours, which, however, regresses at once on cessation of treatment so that by the end of the 4th day the ovary again approximates its infantil...

The collagenous domain of bovine glomerular basement membrane was excised in soluble form by limited pepsin digestion and characterized. The domain amounts to approximately 25% of the whole membrane by weight. The constituent polypeptides were studied using several electrophoresis systems and amino acid analysis. The electrophoresis systems used were a combination of agarose and polyacrylamide...

The digestion and absorption of collagen, native and artificially cross-linked, has been examined in the rat and the Gaboon viper, by feeding known quantities and measuring the hydroxy-proline content of the faeces and of the contents of the gut at different levels, and comparing with an unabsorbable marker (polyethylene glycol). Incubation of collagen in vitro with pepsin at 37 degrees C at pH...

Chromosomes and nuclei isolated from neutral formalin-fixed Vicia faba lateral roots were treated with trypsin, pepsin, RNase, or DNase. Only trypsin affected the morphology of the chromosomes and nuclei. The appearance of the chromosomes after trypsin digestion indicated that each chromatid contained four strands that could be seen with an ordinary light microscope. The experiments are interpr...