Robust unfolding of MeV x-ray spectra from filter stack spectrometer data.

We present an inversion method capable of robustly unfolding MeV x-ray spectra from filter stack spectrometer (FSS) data without requiring an a priori specification of a spectral shape or arbitrary termination of the algorithm. Our inversion method is based upon the perturbative minimization (PM) algorithm, which has previously been shown to be capable of unfolding x-ray transmission data, albeit for a limited regime in which the x-ray mass attenuation coefficient of the filter material increases monotonically with x-ray energy. Our inversion method improves upon the PM algorithm through regular smoothing of the candidate spectrum and by adding stochasticity to the search. With these additions, the inversion method does not require a physics model for an initial guess, fitting, or user-selected termination of the search. Instead, the only assumption made by the inversion method is that the x-ray spectrum should be near a smooth curve. Testing with synthetic data shows that the inversion method can successfully recover the primary large-scale features of MeV x-ray spectra, including the number of x-rays in energy bins of several-MeV widths to within 10%. Fine-scale features, however, are more difficult to recover accurately. Examples of unfolding experimental FSS data obtained at the Texas Petawatt Laser Facility and the OMEGA EP laser facility are also presented.

Cataract-related changes in protein aggregates of human lens studied by ultracentrifugation.

In human lens, cataract development causes an increase in the amount of protein aggregates. Their specific density of 1.25 g/ml is much higher than that of 1.14 g/ml and 1.06 g/ml obtained for water-soluble proteins. During the formation of water-insoluble aggregates their size varies up to some micrometers. Infrared spectra of water-soluble protein and in the aggregates confirm that the content of bound water in aggregates decreases.

An isoelectric focusing study of acid phosphatase heterogeneity in rat liver.

The different forms of acid phosphatase (EC 3.1.3.2) in rat liver homogenates, lysosomal, mitochondrial, microsomal fractions and cytosol were studied with isoelectric focusing. Evidence is presented that isoelectric focusing of acid phosphatase in subcellular fractions shows individual changes and time related patterns. Mild autolysis shifted all enzyme activity peaks of isoelectric focusing patterns to the one at pH 7.04.

Raman and infrared studies of homogeneous forms of acid phosphatase from rat liver.

Raman spectra of acid phosphatase (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2) forms from rat liver in water solution, and infrared spectra of the same forms as thin films, have been investigated. The spectra show strong bands belonging to phosphodiester or phosphomonoester residues. These groups are modified during the postsynthetic modification of acid phosphatase and are probably connected with the process of bonding and splitting of mannose 6-phosphate and N-acetylglucosamine, in agreement with previous biochemical models for the intracellular transport of newly synthesized lysosomal hydrolases to lysosomes. Some other bands in the infrared spectra are assigned to vibrations of N-H groups which may belong to N-acetylglucosamine.

Rhythmic variations in acid phosphatase activity in the liver of newborn rats.

The rhythm of acid phosphatase activity in liver homogenates of newborn rats (aged about 14 days) was compared with a similar rhythm in adult rats (aged 4.5 months). Serial chromatographic investigations demonstrating isoenzyme patterns demonstrated age-related changes of this rhythm connected with the synthesis of the enzyme in newborn rats. The averaged activity of the enzyme in the liver homogenates of newborn rats was about 4 times lower than in adult rats. The maximal values of total enzyme activity of both isoenzymes after chromatographic separation in newborn rats were shifted by about 7 hours in relation to adult animals. Similar changes were observed in the case of the greatest maximal values of the activity ratios--subunit: both isoenzymes, and isoenzyme II: isoenzyme I. In adult rats these maximal values appeared during the night hours and in newborn rats during the day.

Rhythmic changes of some lysosomal hydrolases activity from rat liver. Rhythmic changes of acid phosphatase synthesis.

The activity of acid phosphatase (E.C.3.1.3.2.), arylsulfatase (E.C.3.1.1.23.), beta-galactosidase (E.C.3.1.1.23.), and beta-acetylglucosaminidase (E.C.3.2.1.30.) in rat liver homogenates of 4.5 month-old male rats is presented in this paper. The degradation processes are observed in rat liver homogenate after incubation. The activity of acid phosphatase and beta-acetylglucosaminidase increases, the activity in one of beta-galactosidase is constant, and arylsulfatase decreases during the time of incubation. Furthermore, the maxima of the enzyme activities shift during the incubation in the time of a day. Gel filtration of acid phosphatase on the Sephadex G-150 Superfine and DEAE-cellulose columns determinate the mutual content of acid phosphatase subunits to isoenzymes I and II in various points of a day. The greatest content of acid phosphatase subunits versus both the isoenzymes content is at 02(24), and the greatest content of isoenzyme II versus the content of isoenzymes I appears at 07(12). From these data it is clear that the period of the isoenzyme II synthesis from the subunit amounts to 5 h, while 10 h are necessary to create the isoenzyme I originated from isoenzyme II. The comparison of acid phosphatase activity before and after the homogenate filtration on the Sephadex column indicates the increase of this enzyme activity after its separation from the other proteins and other components.

Far infrared spectra of acid phosphatase from rat liver. Spectra of the native and the heat- and acid-denatured isoenzymes.

The spectrum of acid phosphatase, as well as that of its isoenzymes, shows in the region 100-500 cm-1 a band at 362 cm-1 which appears to be due to second-order structure (alpha-helix). The character of these spectra is unchanged by deuteration of the protein. Heat- and acid-denaturation affected all the spectra studied pointing to the occurrence of conformational changes, but a close similarity between the spectra of the two isoenzymes was consistently observed.

Laser Raman spectroscopy of acid phosphatase from rat liver after neuraminidase treatment.

The conventional Raman technique was used to obtain spectra of acid phosphatase isoenzymes I and II from rat liver after neuraminidase enzyme treatment for 24 h. The low frequency bands below 300 cm-1 which were observed in native lyophilized isoenzymes are obtained from the sialic acid groups of these glycoproteins. These bands disappeared after neuraminidase treatment and the broad bands at 310, 260, 200 and 80 cm-1 are obtained from protein modes. The small differences between the Raman spectra of these isoenzymes disappeared after the neuraminidase treatment.

Laser raman spectroscopy of arylsulphatase B from rat liver.

1. The Raman spectra of native and denatured arylsulphatase B in aqueous solutions are reported. 2. Acid denaturation in 1 M-HCl solution (pH 1.2) was observed 1, 4 and 24 h after dissolution of the enzyme. 3. Changes in the geometry of the disulphide bridges and unfolding of the protein coil were observed. The observed decrease in the intensity of the tyrosine peaks indicates that these amino acid residues were shifted out.