Preliminary results concerning the presence of secretory immunoglobulin A (SIgA) in the serum of patients with IgA myeloma.

Using the immunosorbents realized by binding either antisecretory immunoglobulin A antibodies or antisecretory component ones to beads of cross-linked polyvinyl alcohol matrix, secretory immunoglobulin A, from the serum of patients with IgA myeloma was investigated. The related protein isolated with the same method from colostrum was comparatively studied. Studies were done by polyacrylamyde gel electrophoresis (PAGE) and SDS-PAGE, as well as by immunochemical methods. The two proteins obtained presented the same characteristics: a single fraction in PAGE and four fractions in SDS-PAGE. The determinations were carried out by immunoelectrophoresis and double diffusion using monospecific antisera proved the identity of the isolated proteins with secretory IgA.

All-reagent test tablets and method for rapid and selective alpha-amylase iodometric determination.

The new type of test tablets (Iodocrom) for alpha-amylase assay contain crosslinked (CL)-amylose or CL-starch (specific substrates for alpha-amylase only) and the reagent (KIO3/KI) generating iodine (in acidic medium, when the reaction is stopped). The method--amyloclastic in nature--is based on selective action of alpha-amylase on the CL-substrate liberating soluble polysaccharide chains large enough and in a conformation suitable to allow the formation of iodine inclusion complexes. Unlike the classical iodometric methods, the reaction is followed by an increase in iodine complex blue color. The method has some common points with the well-known chromogenic (e.g., Phadebas) methods. Both use insoluble substrates which are not susceptible to attack by exoamylases and in both cases the enzymatic reaction is followed by the release of soluble products. The amounts of these released chains and the absorbances of their inclusion complexes with iodine are in a linear dependence with the enzyme concentration (activity).

[Covalent binding of peroxidase to CH- and AH-Sepharose 4 B]. / Kovalente Bindung von Peroxidase an CH- und AH-Sepharose 4 B

The properties of peroxidase insolubilized by covalent binding to CH- and AH-Sepharose 4 B in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) are described. CH-Sepharose 4 B bound peroxidase yields an enzyme preparation with a residual specific activity of 60.6%. When bound to AH-Sepharose 4 B, the residual specific activity is to 78%. The reasons of these differences in the catalytic activity of the two insolubilized enzyme preparations are discussed. By covalent binding on CH- and AH-Sepharose 4 B, peroxidase exibits no changes in its pH optimum; it virtually keeps the same activity after being used ten times. Insolubilized peroxidase preparations, dried and reimbibed after being stored for 6 weeks at room temperature still display 50% of the initial specific activity of the insolubilized enzyme. Stored in acetate buffer, the enzyme preparations maintain their activity during all this interval.