A fluorometric assay for pepsin and pepsinogen was developed using enhanced green fluorescent protein (EGFP) as a substrate. Acid denaturation of EGFP resulted in a complete loss of fluorescence that was completely reversible on neutralization. In the proteolytic assay procedure, acid-denatured EGFP was digested by pepsin or activated pepsinogen. After neutralization, the remaining amount of un...

The ingestion of nucleic acids (NAs) as a nutritional supplement or in genetically modified food has attracted the attention of researchers in recent years. Discussions over the fate of NAs led us to study their digestion in the stomach. Interestingly, we found that NAs are digested efficiently by human gastric juice. By performing digests with commercial, recombinant and mutant pepsin, a prote...

Inhibitory activities against angiotensin I-converting enzyme (ACE) of enzymatic hydrolysates of porcine skeletal muscle proteins were investigated. Myosin B, myosin, actin, tropomyosin, troponin and water-soluble proteins extracted from pork loin were digested by eight kinds of proteases, including pepsin, α-chymotrypsin, and trypsin. After digestion, hydrolysates produced from all proteins sh...

A three-step in vitro procedure was developed to estimate intestinal digestion of proteins in ruminants. Dacron bags containing feed samples were suspended in the rumen for 16 h. Residue containing 15 mg of N after ruminal exposure was incubated for 1 h in 10 mL of a .1 N HCl solution containing 1 g/L of pepsin. After incubation, pH was neutralized with .5 mL of 1 N NaOH and 13.5 mL of a pH 7.8...

Peptide mapping of antibodies is an essential method to monitor peptide modifications in antibody lots that could affect the safety and efficacy product. Conventional protocols rely on protein digestion using proteases, such as trypsin, before with mass spectrometry (MS). However, trypsin may cause incomplete peptides, especially those include highly hydrophobic peptides. Here, we show how peps...

1. Of the three major human pepsins, pepsin 1 has greater proteolytic activity towards ovalbumin than has pepsin 3. Pepsin 5 has low activity towards this substrate. 2. Proteolytic pH-activity curves show only on pH maximum, about pH 1.4 for pepsin 1, pH 1.4--1.5 for pepsin 3 and pH 1.2--1.4 for pepsin 5. The curve for pepsin 3 has a shoulder between pH 2.4 and 3.4. 3. The rate of digestion of ...

A protein fraction has been isolated from crude pepsin preparations which is about 400 times as active as crystalline pepsin in the lique-faction of gelatin. The activity as measured by the digestion of casein, edestin or egg albumin is less than that of crystalline pepsin. It is more resistant to alkali than the crystalline pepsin.

A system for the production of soluble porcine pepsinogen A (EC 3.4.23.1) was developed by fusing the pepsinogen and thioredoxin genes and then expressing the fused product (Trx-PG) in Escherichia coli. The expressed fusion protein was purified using a combination of ion-exchange and hydrophobic chromatography. Trypsin digestion of the fusion protein yielded pepsinogen which was one residue lon...

1. At equal hydrogen ion concentration the rate of pepsin digestion of gelatin, egg albumin, blood albumin, casein, and edestin is the same in solutions of hydrochloric, nitric, sulfuric, oxalic, citric, and phosphoric acids. Acetic acid diminishes the rate of digestion of all the proteins except gelatin. 2. There is no evidence of antagonistic salt action in the effect of acids on the pepsin d...