Isolation and Characterization of Proteinases from the Sarcocarp of Snake-Gourd Fruit

Abstract

Seven proteinases were isolated from the fruit of snake-gourd, Trichosanthes cucumeroides Maxim. Their isozymes are all serine proteinases, and homologous in their respective molecular weights, amino acid compositions, and enzymatic properties. Their molecular weight was estimated to be about 50,000. Using casein as a substrate, the maximum activity was found in the alkaline pH region. The optimum temperature using casein was 70 degrees C at pH 7.3. The enzymes were strongly inhibited by diisopropyl fluorophosphate and not inhibited by inhibitors of sulfhydryl or metalloproteases. The reduced and S-carboxymethylated insulin B-chain was used as a substrate in an investigation of the specificity. The enzyme was found to have a wide specificity for this substrate but preferentially hydrolyzed the peptide bonds involving the carboxyl groups of charged amino acid such as S-cm-cysteine, glutamic acid, histidine, arginine, and lysine. Experimental evidence indicated that the snake-gourd proteinases are similar in their properties to cucumisin, which is isolated from the sarcocarp of melon fruit.

Taraxalisin – a serine proteinase from dandelion Taraxacum officinale Webb s.l

“…The molecular mass of the enzyme equal to 67 kDa was determined by gel filtration. It is comparable with the values found for other plant serine endopeptidases [8–13]. Isoelectric point of the enzyme is at pH 4.5.…”

Macluralisin ? a serine proteinase from fruits of Maclura pomifera (Raf.) Schneid.

“…Nepenthes pitchers (Lobareva et al 1973) and a metalloproteinase from soybean leaves (McGeehan et al 1992), subtilisin-like enzymes from Helianthus (Rudenskaya et al 1987) and several cucurbitaceous plants (Kaneda and Tominago 1977;Kaneda et al 1984Kaneda et al , 1986Curotto and Gonzalez 1989;Uchikoba et al 1990) should be mentioned. The latter results are especially interesting as subtilisins used to be considered as a family of predominantly bacterial enzymes and only recently have representatives of this family been found in animals (Barr 1991).…”

Isolation and Characterization of a Possible Native Cucumisin from Developing Melon Fruits and Its Limited Autolysis to Cucumisin

“…Prince),ll white gourd (Benincasa cerifera),2l and snake gourd (Trichosanthes cucumeroides Maxim) 3 l contain significant amounts of a serine proteinase. The enzyme isolated from the sarcocarp of Prince melon is called cucumisin.…”