Biomedical subjects
Publications and source records attributed to C A Ryan.
Proteinase inhibitors, purified independently from Japanese, United States, and German potato varieties, and having different physicochemical and inhibitory properties, are shown to be immunochemically similar. These results indicate that the heterogeneity found among proteinase inhibitors from potato tubers is apparently due both to intervarietal, as well as intravarietal, variations in isoinhibitor components.
The structure of the complex between anhydro-trypsin and pancreatic trypsin inhibitor has been determined by difference Fourier techniques using phases obtained from the native complex (Huber et al., 1974). It was refined independently by constrained crystallographic refinement at 1.9 A resolution. The anhydro-complex has Ser 195 converted to dehydro-alanine. There were no other significant structural changes. In particular, the high degree of pyramidalization of the C atom of Lys 15 (I) of the inhibitor component observed in the native complex in maintained in the anhydro-species.
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An assay has been developed for the proteinase inhibitor-inducing factor (PIIF), a wound hormone. PIIF is present in tomato (Lycopersicum esculentum var. Bonnie Best) leaf extracts and induces accumulation of proteinase Inhibitor I when the extracts are supplied briefly to excised leaves that are subsequently incubated in water under constant light. An active water-soluble crude PIIF solution was conveniently prepared from autoclaved and lyophilized tomato leaves. Accumulation of Inhibitor I, induced by crude PIIF, is linear, commencing at about 8 to 10 hours after feeding and continues for several hours. Evidence is presented that the PIIF-induced accumulation of Inhibitor I, determined immunologically, is accompanied by the accumulation of other trypsin and chymotrypsin inhibitors, determined enzymatically. The accumulation of Inhibitor I is inhibited by actinomycin D and cycloheximide but not by chloramphenicol or rifampin. PIIF cannot be replaced by traumatin, indoleacetic acid, gibberellic acid, kinetin, ethylene, or abscisic acid. PIIF activity was not destroyed by incubation with a number of proteolytic, carbohydrase, phosphatase, or pyrophosphatase enzymes. The active substance is insoluble in lipid solvents.
Thirty-nine plant species representing 20 families from the four major divisions of plants were surveyed for the presence of proteinase inhibitor-inducing factor activity in leaves or other tissues. Tissue juices were assayed for their capacity to induce accumulation of proteinase inhibitor I in excised tomato (Lycopersico esculentum) leaves. In tissues of only 2 of the 39 species was proteinase inhibitor-inducing factor-like activity not found. The activity was absent in cabbage leaves and celery stalks. Fruiting bodies from one of three fungi genera assayed contained exceptionally large quantities of proteinase inhibitor-inducing factor-like activity. Extracts from Agraricus campestris fruiting bodies contained over 20 times more activity than tomato leaf juice. The survey confirms that substances with proteinase inhibitor-inducing factor-like activity are widespread in the plant kingdom.
Wounding of single leaflets of young tomato (Lycopersicum esculentum var. Bonnie Best) plants causes the release of a proteinase inhibitor inducing factor. This factor is rapidly transported throughout the plant where it causes accumulation of inhibitor I, a potent inhibitor of several serine proteinases from both animals and microorganisms. The wound-induced accumulation of inhibitor I is both light- and temperature-dependent. In total darkness no accumulation results from wounding. The accumulation exhibits a linear dependence upon light up to 300 foot candles. At 600 foot candles and above, the response is maximal. In light the wound response possesses an unusual temperature dependence with an optimum rate of accumulation near 36 C. Below 20 C no accumulation occurs. The over-all process contains two light- and temperature-dependent steps, one involving wounding and transport, the other involving accumulation.
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Microcomplement fixation was employed to compare the immunological differences that occur between purified inhibitor I from potato tubers, the four purified protomers that comprise it, and inhibitor I from tuber and leaf extracts. Total inhibitors of chymotrypsin and trypsin in leaves of seven genera of the Solanaceae were identified by enzymatic assay. In leaves of three genera, Solanum, Lycopersicum, and Datura, chymotrypsin inhibitor I was identified immunologically. In petals of all seven genera inhibitor I was also identified immunologically. With the microcomplement fixation technique inhibitor I from leaf or petal extracts of eight Solanaceae genera were compared. An immunological relationship of inhibitor I among seven of these genera was established.
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The synthesis and accumulation of chymotrypsin inhibitor I in tomato leaflets is induced by detachment, or by destruction of petiole phloem by steam when followed by incubation of the leaflets in light. The induction process with detached tomato leaflets is similar to that found with detached potato leaflets. The large amount of inhibitor I synthesized per leaflet cell per unit time suggests either that the structural gene is redundant or that an unusually stable messenger RNA is present. In both tomato and potato leaflets the accumulation of inhibitor I is potently inhibited by actinomycin D, puromycin, and cycloheximide, but not by chloramphenicol. Indoleacetic acid is moderately inhibitory, as is 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Glutamine and asparagine are both markedly stimulating. The cumulative data suggest that inhibitor I is a major depot or interim storage protein and that its existence in any particular tissue is under complex controls by both the internal and external environments of the plants.