• Microbiology and Biotechnology Letters
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• v.17 no.2
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• pp.121-125
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• 1989

Actinomycetes GF 155-2, which produced an extracellular pepsin inhibitor, was isolated from soil samples. Optimal conditions of inhibitor production by flask-shacking culture were 2% glucose, 0.7% polypeptone, initial pH 1.0, culture time 60 hours and temperature 30%. Effect of in-organic salts was not observed. About 5mg of colorless crystalline inhibitor was obtained from 5L culture broth in jar tormentor by means of ammonium sulfate precipitation, methanol extraction, and column chromatographies on Amberlite IR-120, XAD-2 and silicagel 60.

• Microbiology and Biotechnology Letters
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• v.17 no.2
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• pp.115-120
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• 1989

For the purpose of obtaining microorganisms which produced an extracellular pepsin inhibitor, screening test was carried out. One strain of Actinomycetes (GF 155-2) isolated from soil samples showed a high inhibitory activity against porcine pepsin. The morphological, physiological and cultural characteristics of the strain GE 155-2 on various culture media were studied according to ISP methods and Bergey's manual of determinative bacteriology (8th ed.). This Actinomycetes GE 155-2 was found to be similar to the genus Microtetraspora.

• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.496-500
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• 1990

When pepsin was used at a concentration of 8 mglml for hydrolysis of 0.02% casein, inhibitory activity of this inhibitor was proportional to a inhibitor concentration of 20 ${\mu}g$/ml, and fifty percent inhibition ($IC_{50}$) was observed to be 15 ${\mu}g$/ml. The inhibitor was pH-stable at pH range of 5-9 at $100^{\circ}C$ for 10 minutes and thermo-stable at pH 7.0 at $100^{\circ}C$ to give 100% activity for 20 minutes. The formation of pepsin-inhibitor complex was confirmed by sephadex 6-25 gel filtration and type of inhibition was determined as non-competitive inhibition by Lineweaver-Burk plot. The inhibitor strongly inhibited acid proteases such as pepsin and renin, and it was soluble in methanol very well. On TLC analysis of silicagel 60 using various sohent systems, the inhibitor gave a single spot at Rf range 0.4-0.6. From the result of IR spectrum and color reaction (Rydon-Smith, Biuret), this inhibitor was considered as peptide substance. Melting point and elemental contents were 220-$230^{\circ}C$, and C 50.61%-H 8.02%-N 9.34% (found), respectively.