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Biomedical subjects

V A Laurinavichius

Publications and source records attributed to V A Laurinavichius.

4 recordsLinked to original sources
PubMed1989

[A rapid analyzer for determining blood urea].

An express analyzer for urea measurements has been designed on the basis of the Exan-G glucose analyzer. The measurement bases on the potentiometric analysis of urease-immobilized urea hydrolysis. The detector consists of a flat pH electrode and an enzymic membrane. The sample volume is 50 microliters of whole blood, the measurement limit is 2-40 mM; 30 samples can be analyzed in an hour; the coefficient of variations is 3%. The optimal conditions of the measurements have been defined.

Blood Chemical Analysis↗
PubMed1980

[Determination of penicillins by means of an enzymatic electrode].

Penicillin sensitive enzyme electrodes were prepared on the basis of native penicillinase (EC 3.5.2.6) and penicillinamidase (CE 3.5.1.11), as well as penicillinase entrapped in a complex of polyethylenimine and polyacrylic acid or linked with albumin and lattice entrapped penicillinase. The time of the electrode response is 2-10 minutes. The electrode potential change within a minute is linear at 1-20 mM of benzylpenicillin and depends on the electrode type. The electrodes prepared on the basis of the native enzymes lost their sensitivity within the first 10 days. Sensitivity of immobilized penicillinase did not change for 15 days. The electrodes prepared on the basis of albumin-linked penicillinase preserved their high stability for 60 days. The sensitivity of these electrodes is slightly dependent on the phosphate buffer concentration (from 0.001 to 9 mM).

Buffers↗
PubMedDate not supplied

[Enzyme immobilization on hydrated oxides of transition metals and aluminum].

The immobilization of alpha-chymotrypsin, trypsin and invertase on hydrated oxides of tin, titanium and aluminium was investigated. The degree at which the enzymes were bound upon immobilization was 83.2-2.6%. The amount of bound proteins was 64.2 mg/g carrier. The specific activity of enzymes reached the highest level in the case of hydrated tin oxide and amounted to 76.8%, 49.9% and 99.6%, of activity of native alpha-chymotrypsin, trypsin and invertase, respectively. The thermal stability of immobilized proteases was considerably higher and that of immobilized invertase was significantly lower than that of native enzymes. The pH optimum of immobilized enzymes shifted by 0.6-2.6 units towards the alkaline region.

Aluminum↗