Immunochemical evaluation of radioiodinated protein A

The [125I]iodoprotein A iodinated by the chloramine-T method using carrier-free 125I- to various specific activities (0.02-2.0 125I/mole protein A) displayed 85% binding activity to excess solid-phase rabbit IgG. On storage, however, the solid-phase IgG binding activity of the high specific activity [125I]iodoprotein A (approximately 2 125I/protein A) decreased rapidly while that of the low specific activity [125I]iodoprotein A (approximately 0.2 125I/protein A) remained essentially unchanged. Analysis of aged high specific activity [125I]iodoprotein A by thin-layer chromatography revealed that free 125I- was released from the [125I]iodoprotein A during storage. Removal of the released 125I- was accomplished by using anion exchange resin. High specific activity [125I]iodoprotein A was found to be more sensitive than the low specific activity [125I]iodoprotein A in quantitating aggregated IgG while the latter was as useful as the former in hybridoma screening. When protein A was labeled with the Bolton-Hunter reagent, the [125I]iodoprotein A had an IgG binding property and stability similar to the [125I]iodoprotein A labeled with the chloramine-T method. Since the chloramine-T method can yield high specific activity [125I]iodoprotein A and repurification of the aged preparation can easily be achieved by using anion exchange resin, we concluded that chloramine-T is more efficient than Bolton-Hunter reagent and that both methods yield materials with comparable immunochemical properties.

Plasma alpha 1-acid glycoprotein levels in pregnancy

One hundred and five determinations of plasma alpha 1-acid glycoprotein (alpha 1AG) levels in 96 women with normal pregnancies were done by an enzyme-linked immunosorbent assay developed in this laboratory. Plasma alpha 1AG levels in pregnant women of all trimesters and 4-10 weeks post-partum period do not differ significantly from those obtained from healthy women of child bearing age. In nine women whose pregnancies were complicated by acute inflammation, plasma levels of alpha 1AG were significantly higher. These findings suggest that in normal pregnancy, alpha 1 AG levels in the plasma remain unchanged. But, pregnancy does not obscure alpha 1 AG response to acute inflammation.

A solid-phase enzyme-linked immunosorbent assay for the quantitation of human plasma alpha 1-acid glycoprotein

We describe a solid-phase enzyme-linked immunosorbent assay for alpha 1-acid glycoprotein in human plasma. Plasma samples are incubated with alkaline phosphatase-linked, purified alpha 1-acid glycoprotein in alpha 1-acid glycoprotein-specific antibody-coated polystyrene tubes. The alkaline phosphatase that becomes attached to the tube via an immunological reaction between the alpha 1-acid glycoprotein and the specific antibody is measured spectrophotometrically. This assay is accurate reproducible, simple, and economical. As little as 4 microgram of alpha 1-acid glycoprotein per liter can be detected. The normal range for alpha 1-acid glycoprotein in the plasma of healthy adults, as measured by this method, is 0.48-1.27 g/L; the range is significantly different, 0.29-0.73 g/L, for women who are taking oral contraceptive pills.

A solid-phase enzyme-linked immunosorbent assay for the quantitation of human plasma alpha 1-acid glycoprotein

We describe a solid-phase enzyme-linked immunosorbent assay for alpha 1-acid glycoprotein in human plasma. Plasma samples are incubated with alkaline phosphatase-linked, purified alpha 1-acid glycoprotein in alpha 1-acid glycoprotein-specific antibody-coated polystyrene tubes. The alkaline phosphatase that becomes attached to the tube via an immunological reaction between the alpha 1-acid glycoprotein and the specific antibody is measured spectrophotometrically. This assay is accurate reproducible, simple, and economical. As little as 4 microgram of alpha 1-acid glycoprotein per liter can be detected. The normal range for alpha 1-acid glycoprotein in the plasma of healthy adults, as measured by this method, is 0.48-1.27 g/L; the range is significantly different, 0.29-0.73 g/L, for women who are taking oral contraceptive pills.

Cytochrome P-450 from mitochondria of bovine adrenal cortex: comparison of cholesterol side-chain cleavage P-450 with steroid 11beta-hydroxylation P-450 and immunochemical cross-reactivity between adrenal mitochondrial and liver microsomal cytochromes P-450

Adrenocortical mitochondrial cytochrome P-450 specific to the cholesterol side-chain cleavage (desmolase) reaction differs from that for the 11beta-hydroxylation reaction of deoxycorticosterone. The former cytochrome appears to be more loosely bound to the inner membrane than the latter. Upon ageing at 0 degrees C or by aerobic treatment with ferrous ions, the desmolase P-450 was more stable than the 11beta-hydroxylase P-450. By utilizing artificial hydroxylating agents such as cumene hydroperoxide, H2O2, and sodium periodate, the hydroxylation reaction of deoxycorticosterone to corticosterone in the absence of NADPH was observed to a comparable extent with the reaction in the presence of adrenodoxin reductase, adrenodoxin and NADPH. However, the hydroxylation reaction of cholesterol to pregnenolone was not supported by these artificial agents. Immunochemical cross-reactivity of bovine adrenal desmolase P-450 with rabbit liver microsomal P-450LM4 was also investigated. We found a weak but significant cross-reactivity between the adrenal mitochondrial P-450 and liver microsomal P-450LM4, indicating to some extent a homology between adrenal and liver cytochromes P-450.

Purification and characterization of adrenal cortex mitochondrial cytochrome P-450 specific for cholesterol side chain cleavage activity

Cytochrome P-450 was purified from bovine adrenal cortex mitochondria by affinity chromatography using an octylamine-substituted Sepharose column. The resulting optically clear preparation was stable at -20 degrees for months. The specific concentration of cytochrome P-450 in the preparation was about 5 nmol of heme per mg of protein. The preparations were free of adrenodoxin, adrenodoxin reductase, phospholipids, and other heme contaminations. Polyacrylamide gel electrophoresis of the purified cytochrome P-450 preparation treated with sodium dodecyl sulfate and mercaptoethanol showed a single major band with a molecular weight of about 60,000. The optical absorption spectra of the preparation exhibited Soret maxima at 416, 416, and 448 nm for the Fe3+, Fe2+ and the C.Fe2+ complex, respectively. The EPR spectrum showed the characteristic features of the low spin form of ferric cytochrome P-450 with principal components 1.914, 2.241, and 2.415 of the g-tensor. The circular dichroism spectrum revealed two large negative ellipticities at 412 and 350 nm. Fluorescence spectra showed an excitation maximum at 285 nm and an emission maximum at 305 nm with a shoulder at 330 nm as the cytochrome P-450 molecule is excited at 285 nm, or an emission maximum at 335 nm when the cytochrome molecule is excited at 305 nm. After reconstitution with adrenodoxin and its reductase, this cytochrome P-450 was highly active for cholesterol desmolase with an NADPH-generating system as electron donor but was not active for steroid 11beta-hydroxylase.

Ferrous ion-mediated cytochrome P-450 degradation and lipid peroxidation in adrenal cortex mitochondria

The relationship between the degradation reaction of cytochrome P-450 and lipid peroxidation was studied utilizing bovine adrenal cortex mitochondria. The two reactions were found to be closely correlated in terms of their response to storage of the mitochondrial preparation, stimulation by Fe2+, inhibition by EDTA and their initiation by cumene hydroperoxide. Both reactions were also found not to be inhibited by catalase, superoxide dismutase, 1,4-diazabicyclo-(2,2,2)-octane and alcohols, indicating that H2O2, superoxide, singlet oxygen and hydroxyl radicals do not participate in these reactions. Yet, diphenylamine proved to be a powerful inhibitor for both reactions, suggesting the involvement of a radical species. Cumene hydroperoxide could induce these two reactions at below 0.1 mM concentrations in the presence of molecular oxygen. The chemiluminescence observed during the Fe2+-mediated lipid peroxidation reaction which was not inhibited by either superoxide dismutase or 1,4-diazabicyclo-(2,2,2)-octane, was biphasic: one was a rapid burst; and the other was a slowly increasing emission. The latter portion of the emission of light coincided with the formation of malondialdehyde. These results indicate that in adrenal cortex mitochondria the degradation of cytochrome P-450 is closely related to lipid peroxidation.