Volume 11, Issue 6
June 1940, pages 225-289
pp 225-235 June 1940
pp 236-247 June 1940
pp 248-256 June 1940
As a preliminary to a purification and study of the nature of the enzyme, methods for a quantitative estimation of tyrosinase have been standardised. The O2-uptake with mono- and di-hydroxy phenols has been studied in this connection. While the direct oxidation of phenol andp-cresol serves admirably as a measure of the enzyme, the oxidation of catechol fails to fulfil the conditions. To secure a steady rate of O2-uptake proportional to enzyme concentration, the direct oxidation of catechnol cannot be adopted but the oxidation of either ascorbic acid or hydroquinone (or ferricyanide) through the agency of catechol as “carrier”, fulfils the requirements. The formation of quinone bodies, the products of oxidation of various substrates by the enzyme, could be followed also iodimetrically.
The general substrate specificity of the enzyme suggests that it is not a “laccase” since the enzyme preparations have been found to be inert towardsp-dihydroxy compounds. The fact that the enzyme preparations oxidise several mono- and di-hydric phenols, necessitates a deeper study of the influence of further purifications on substrate specificity.
pp 257-266 June 1940
Glutathion determinations, hæmoglobin estimations and erythrocyte counts have been made with the venous blood of each of 40 anæmic patients; Gabbe’s and modified Gabbe’s quotients calculated.
The values range from (i) 11·96 to 48·90 mgm. for reduced glutathion; (ii) traces to 19·63 mgm. for oxidised glutathion in 100 c.c. of blood; (iii) 2·3 to 14·8 gm. for 100 c.c. blood for hæmoglobin; and (iv) 0·51 to 5·03 millions per mm.3 for the erythrocyte count. Gabbe’s quotient tends to be high with low counts and appears to follow an exponential curve. Modified Gabbe’s quotient tends to oscillate between narrow limits suggesting the possibility of an interrelationship between the hæmoglobin and the glutathion in the blood.
There is a marked increase in the corpuscular glutathion in anæmias generally and in ankylostome anæmias the increase is higher.
pp 267-288 June 1940
The physiology of the black tip disease of mangoes (Mangifera indica) has been studied with respect to ethylene, and sulphur dioxide, the two important and harmful constituents of blast furnace gas.
The respiratory rate, sugar and acid contents of 30–100 days old mangoes have been studied. It was found that—
Ethylene-air mixture accelerated after an induction period of 15 hours or more, depending on the age of the fruit, the respiratory rate and increased the sugar content, but it did not affect the total acid content of the fruit. Mangoes treated with ethylene generally became soft and yellow;
The induction period was very much decreased if the skin was peeled off before the experiment;
Prolonged treatment with a strong concentration of ethylene gas produced the characteristic black-tip disease of the mango;
Sulphur dioxide-air mixture also had an induction period and accelerated the respiratory rate, but had an adverse effect on the general condition of mangoes;
Ethylene-sulphur dioxide-air mixture increased the respiratory rate and sugar content, but made the mesocarp, especially its lower half, soft, pulpy and disorganized, and produced the black-tip disease of mangoes.
pp 289-289 June 1940 Erratum