PT  - JOURNAL ARTICLE
AU  - Rodis, Panayotis
AU  - Hoff, Johan E.
TI  - Naturally Occurring Protein Crystals in the Potato
AID  - 10.1104/pp.74.4.907
DP  - 1984 Apr 01
TA  - Plant Physiology
PG  - 907--911
VI  - 74
IP  - 4
4099  - http://www.plantphysiol.org/content/74/4/907.short
4100  - http://www.plantphysiol.org/content/74/4/907.full
SO  - Plant Physiol.1984 Apr 01; 74
AB  - Protein crystals isolated from potato tubers were found to consist of a proteinase inhibitor active against the cysteine proteinases papain, chymopapain, and ficin. The molecular weight as determined by gel filtration at pH 4.3 or by gel electrophoresis in the presence of dodecylsulfate was 80 kilodaltons. When the inhibitor was evaluated at pH 8.4 in a linear concentration (4-30% polyacrylamide) under nondenaturing conditions, it appeared as two bands of approximately 320 to 350 kilodaltons indicating that the inhibitor forms tetrameric aggregates in neutral or weakly alkaline media, while the monomeric form predominates under acidic conditions. Gel filtration in the presence of varying amounts of papain suggested that the monomer combines with four papain molecules. The inhibitor contains no cystine.