The Thiol Proteinases from the Latex ofCarica papayaL. III. The Primary Structure of Chymopapain

Abstract

The amino-acid sequence of chymopapain is presented. It was isolated from the latex of the fruits from the tropical species Carica papaya L. and is, besides papain and papaya proteinase , the third thiol proteinase from this source. The primary structure contains 218 amino-acid residues. It was deduced from sequence analysis of the native enzyme and of peptides obtained by tryptic, chymotryptic, peptic, thermolysinolytic and mild acidic hydrolysis. Out of a total of eight cysteine residues, six are involved in the formation of three disulfide bonds, the location of which has been established with the help of peptic and thermolysinolytic peptides and fragments, obtained by mild acidic hydrolysis. Chymopapain shares 126 identical amino-acid residues (58%) with papain and 141 (65%) with papaya proteinase , including the three disulfide bridges and the free cysteine in position 25, required for activity. Except some amino-acid residues in the substrate-binding site, all residues involved in the catalytic mechanism are conserved. The homology between papaya proteinases is discussed. Die Thiol-Proteinasen aus dem Milchsaft von Carica papaya L. III. Die Primärstruktur des ChymopapainsZusammenfassung: Die Aminosäuresequenz des Chymopapains wird angegeben. Es wurde aus dem Milchsaft der Früchte der tropischen Art Carica papaya L. isoliert und ist nach Papain und Papaya-Proteinase die dritte Thiol-Proteinase aus dieser Quelle. Die Polypeptidkette enthält 218 Aminosäurereste. Ihre Primärstruk-tur wurde durch Sequenzanalyse des nativen Enzyms, sowie zahlreicher Pep tide erhalten, die durch tryptische, chymotryptische, peptische, thermolysinolytische und schwach saure Hydrolyse erhalten wurden. Von den insgesamt acht Cysteinresten sind sechs an der Bildung von Disulfidbrücken beteiligt, deren Lage mit Hilfe von peptischen und thermolysinoly tischen Peptiden, sowie von einem durch saure Hydrolyse erhaltenen Fragment bestimmt werden konnte.

Characterization of a partially folded intermediate of stem bromelain at low pH

“…have proposed that bromelain forms may have the same folding pattern shown by other members of the papain family as the spectral characteristics displayed by stem bromelain are similar to those observed in case of papain and proteinase Ω namely, a bilobal structure with predominantlyα and antiparallel β sheet domains [20,21]. Stem bromelain belongs to the α+β protein class as other cysteine proteinases do and the highly identical amino‐acid sequences of papain [22], actinidin [23], proteinase Ω[24,25] chymopapain [26,27] and stem bromelain [28] indicate that the polypeptide chains of these proteins share a common folding pattern. This has been confirmed for the first three proteinases by detailed X‐ray diffraction studies [21,29,30].…”

Factors effecting the thermostability of cysteine proteinases from Carica papaya

“…The publication of the amino acid sequences for chymopapain (Jacquet et al, 1989;Watson et al, 1990) as well as papaya proteinases 3 (papaya proteinase a) and 4 (Dubois et al, 1988;Ritonja et al, 1989) coupled with the 0.18-nm structural data on papaya proteinase 3 (Pickersgill et al, 1991a) has allowed the study of structure/function relationships to be extended directly into the C. papaya family of related cysteine proteinases.…”

Papaya: A gifted nutraceutical plant - a critical review of recent human health research

“…The most important enzyme papain was characterized in 1968 (Drenth et al, 1968). The enzymes chymopapain and papaya protease III were characterized in the 1980s of the last century (Jacquet et al, 1989;Zucker et al, 1985) These two important compounds like papain and chymopapain are supposed to aid in digestion and therefore they are widely used to cure the digestive disorders (Huet et al, 2006). In addition, papain is used in meat tenderizing, pharmaceuticals, beauty products, and cosmetics (EDI, 2012).…”