Kidney rhodanese from the guinea pig (Lepus caniculus) and albino rat (Mus musculus).

Rhodanese (EC 2.8.1.1) has been partially purified from guinea pig and rat kidneys. The specific activities of the preparations were 1.23 and 0.44 mumol of product formed per minute per milligramme of enzyme protein. The guinea pig kidney enzyme had Km values of 14.2 and 31.5 mmol/l for cyanide and thiosulphate, respectively, while for the rat kidney enzyme, these values were 5.7 and 24.4 mmol/l, respectively. The temperature optimum of the enzyme from the two sources was 20 degrees C, while the pH optima were between 7.5 and 8.0. The molecular weight of the guinea pig kidney enzyme was 37,000, while that of the rat was 32,000. The difference in the levels of rhodanese activity in the two types of rodents is discussed in relation to their dietary habits.