Abstract: Method of measuring the amount of .alpha.-amylase in a liquid sample, including the steps of providing an oligosaccharide substrate for .alpha.-amylase, the substrate being characterized in that it contains at least 3 glucose units, its reducing-end glucose unit is bonded, via a bond cleavable by .alpha.- or .beta.-glucosidase, to a label which exhibits an optically measurable change upon cleavage of the bond, and its terminal glucose unit is bonded to a blocking substituent which inhibits cleavage by exo-enzymes of the bond between the terminal glucose unit and the adjacent glucose unit; contacting the sample with the oligosaccharide substrate and with a first exo-enzyme capable of cleaving the bond between the reducing-end glucose unit and the label, and measuring the optically measurable change as a measure of .alpha.-amylase in the sample.

Abstract: Method of measuring the amount of .alpha.-amylase in a liquid sample, including the steps of providing an oligosaccharide substrate for .alpha.-amylase, the substrate being characterized in that it contains at least 3 glucose units, its reducing-end glucose unit is bonded, via a bond cleavable by .alpha.- or .beta.-glucosidase, to a label which exhibits an optically measurable change upon cleavage of the bond, and its terminal glucose unit is bonded to a blocking substituent which inhibits cleavage by exo-enzymes of the bond between the terminal glucose unit and the adjacent glucose unit; contacting the sample with the oligosaccharide substrate and with a first exo-enzyme capable of cleaving the bond between the reducing-end glucose unit and the label, and measuring the optically measurable change as a measure of .alpha.-amylase in the sample.

Abstract: In a method of preparing the enzyme, urease, from jack beans, wherein the jack beans are reduced to a fine particle size and the fine particles so reduced constitute urease, the fine jack-bean particles thereafter irradiated for a period of time, the irradiated jack beans then recovered and employed as a source of urease enzyme, the improvement which comprises: irradiating the whole jack beans prior to any size reduction of the seeds of the jack beans, to provide a urease derived from the white seeds of the irradiated whole jack beans having an improved activity level.

Abstract: A radioassay system for the determination of methotrexate in biological fluids based on the competitive binding of labeled and unlabeled methotrexate to the enzyme dihydrofolate reductase. Samples of unknown methotrexate level are mixed with I.sup.125 labeled methotrexate. A portion of the total methotrexate present is bound by the addition of enzyme, and the unbound methotrexate is removed with charcoal. The level of bound I.sup.125 labeled methotrexate is measured in a gamma counter. To calculate the methotrexate level of the unknown samples, the displacement of bound labeled methotrexate caused by the unknowns is compared to the displacement caused by known methotrexate standards.

Abstract: A method of purifying a protein-reaction mixture to obtain carboxypeptidase G.sub.1, which method comprises: passing the mixture through a column containing support material, such as carboxymethyl cellulose, under pH conditions such that the carboxypeptidase G.sub.1 is preferentially and selectively bonded to active sites on the support material in preference to other protein materials of the mixture; displacing the bound carboxypeptidase G.sub.1 by an eluant, such as a glutamate, which has a greater affinity for the carboxypeptidase G.sub.1 than the support material; and recovering from the column a mixture of the eluant and the carboxypeptidase G.sub.1.

Abstract: A radioassay system for the determination of methotrexate in biological fluids based on the competitive binding of labeled and unlabeled methotrexate to the enzyme dihydrofolate reductase. Samples of unknown methotrexate level are mixed with I.sup.125 labeled methotrexate. A portion of the total methotrexate present is bound by the addition of enzyme, and the unbound methotrexate is removed with charcoal. The level of bound I.sup.125 labeled methotrexate is measured in a gamma ray counter. To calculate the methotrexate level of the unknown samples, the displacement of bound labeled methotrexate caused by the unknowns is compared to the displacement caused by known methotrexate standards.