A high frame rate CCD camera is described, based on the a new, back-thinned, 512/spl times/512 pixel frame transfer sensor with 16 video ports. The sensor allows for imaging beyond the visible range ...within a large dynamic range. Circuits for testing and evaluation of the sensor over a large range of charge transfer clock frequencies and the measured data are presented. The performance of the device when driven to the readout speed limit is also discussed.< >
Cytochrome P-450scc consists of two domains linked with a short loop of the polypeptide chain; under its hydrolysis with trypsin the domains retain their associated state due to rigid noncovalent ...interactions. The structural characteristics of the individual domains have been investigated. It is established that domain I containing the haem and the adrenodoxin-binding site is the N-terminal, and domain II the C-terminal moiety of the polypeptide chain of cytochrome P-450scc.
A sensitive search for direct CP violation in Ξ
− (
Ξ
+) and Λ (
Λ
) decays is underway at FNAL. Experiment E871 (HyperCP) intends to perform a precision measurement of the angular distribution of ...protons (anti-protons) with respect to the helicity axis in the rest frame of the Λ (
Λ
). The slopes of these distributions give the decay parameters
α
Ξ
α
Λ
and
α
Ξ
α
Λ
. An asymmetry parameter
A in terms of these decay parameters has been defined for which a non-zero value would be unambiguous evidence for direct CP violation. Theoretical predictions for
A range from no asymmetry up to ∼ 10
−3. HyperCP expects to measure
A with an uncertainty of ∼ 2 × 10
−4.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, homobifunctional reagent 3,3'-dithiobis (succinimidyl propionate), and heterobifunctional reagent N-succinimidyl ...3-(2-pyridyldithio) propionate have been used to cross-link adrenodoxin reductase and adrenodoxin, components of steroidogenic electron transfer system. Though maximal yield of the cross-linked complex was achieved with the water-soluble carbodiimide, this complex was inactive in the electron transfer from NADPH to cytochrome P-450. The functionally active complex was formed with N-succinimidyl 3-(2-pyridyldithio) propionate. The complex was purified to the apparent homogeneity and shown to be able to mediate the electron transfer. The data obtained indicate existence of different binding sites on adrenodoxin responsible for the adrenodoxin reductase and cytochrome P-450scc binding and do not contradict to the model of the steroidogenic electron transfer in an organized complex.
The interaction between cytochrome P-450scc and adrenodoxin has been studied using cleavable cross-linking reagents and limited trypsinolysis. The data obtained indicate that the site responsible for ...adrenodoxin binding is located on the NH2-terminal fragment F1 of cytochrome P-450scc.
The molecular organization of adrenocortical cytochrome P-450scc has been investigated using chemical modification with bifunctional imidates. The oligomeric organization of cytochrome P-450scc in ...solution has been shown. The application of dimethyl-3,3'-dithiobispropioimidate and subsequent cleavage of the modified products by reducing agents revealed the presence of two types of intramolecular cross-links: "short" at the distance of 3,0 A between the amino groups of lysine residues and "long" ones at a distance of 11,9 A. The analysis of the products, obtained by limited proteolysis of the oligomeric forms of the cross-linked cytochrome P-450, by two-dimensional electrophoresis has shown that the cross-links are formed between the functional domain (fragment F1) and domain responsible for the interaction with the phospholipid membrane (fragment F2). A model for cytochrome P-450scc molecular organization has been suggested on the basis of the obtained results.
Highly specific antibodies against hemeprotein were obtained by immunizing rabbits with a highly purified cholesterol-hydroxylating cytochrome P-450scc from adrenocortical mitochondria. The ...antibodies do not specifically interact with other components of the adrenocortical electron transport chain, e. g., adrenodoxin reductase and adrenodoxin. Using double immunodiffusion technique (Ouchterlony method), it was shown that the antibodies did not precipitate the microsomal cytochromes P-450 LM2 and LM4, cytochrome b5 and 11 beta-hydroxylating cytochrome P-450 from adrenocortical mitochondria. Antibodies against cytochrome P-450scc inhibited the cholesterol side chain cleavage activity of cytochrome P-450scc in a reconstituted system. Limited proteolysis with trypsin and immunoelectrophoresis in the presence of specific antibodies revealed that antigenic determinants are present of the heme-containing catalytic domain of cytochrome P-450scc (F1) as well as on the domain responsible for the interaction with the phospholipid membrane (F2).
Nucl.Instrum.Meth.A541:516-565,2005 The HyperCP experiment (Fermilab E871) was designed to search for rare
phenomena in the decays of charged strange particles, in particular CP
violation in $\Xi$ ...and $\Lambda$ hyperon decays with a sensitivity of
$10^{-4}$. Intense charged secondary beams were produced by 800 GeV/c protons
and momentum-selected by a magnetic channel. Decay products were detected in a
large-acceptance, high-rate magnetic spectrometer using multiwire proportional
chambers, trigger hodoscopes, a hadronic calorimeter, and a muon-detection
system. Nearly identical acceptances and efficiencies for hyperons and
antihyperons decaying within an evacuated volume were achieved by reversing the
polarities of the channel and spectrometer magnets. A high-rate
data-acquisition system enabled 231 billion events to be recorded in twelve
months of data-taking.
