Determinants of Default in P2P Lending

This paper studies P2P lending and the factors explaining loan default. This is an important issue because in P2P lending individual investors bear the credit risk, instead of financial institutions, which are experts in dealing with this risk. P2P lenders suffer a severe problem of information asymmetry, because they are at a disadvantage facing the borrower. For this reason, P2P lending sites provide potential lenders with information about borrowers and their loan purpose. They also assign a grade to each loan. The empirical study is based on loans’ data collected from Lending Club (N = 24,449) from 2008 to 2014 that are first analyzed by using univariate means tests and survival analysis. Factors explaining default are loan purpose, annual income, current housing situation, credit history and indebtedness. Secondly, a logistic regression model is developed to predict defaults. The grade assigned by the P2P lending site is the most predictive factor of default, but the accuracy of the model is improved by adding other information, especially the borrower’s debt level.     

Isolation of bacteriophage T4 baseplate proteins P7 and P8 and in vitro formation of the P10/P7/P8 assembly intermediate.

Two bacteriophage T4 proteins, P7 and P8, which are components of the phage baseplate have been purified to apparent homogeneity. P7 and P8 are the protein products of T4 genes 7 and 8. A plasmid has been constructed which contains approximately 5 kilobases of T4 DNA, including genes 7 and 8, under the control of the tac promoter. Induction of Escherichia coli W3110iQ cells containing this plasmid resulted in the production of functional P7 and P8. Standard protein isolation procedures were used to purify both P7 and P8 from extracts of induced cells. In T4-infected cells, these two proteins and P10 interact in a strictly ordered sequential manner (P10 + P7----P10/P7,P10/P7 + P8----P10/P7/P8) to form an intermediate in the baseplate assembly pathway. The three purified proteins assembled in vitro to form a limited number of oligomeric species, as determined by nondenaturing gel electrophoresis. P10 and P7 interacted in vitro to form two assemblies with distinct electrophoretic mobilities, both containing P10 and P7. Addition of P8 to this mixture resulted in the disappearance of both P10/P7 species and the appearance of a single new assembly with a different electrophoretic mobility. These interactions occurred without the addition of any catalyst or cofactors. Isolated P11 appeared to add as predicted to the in vitro-formed complexes without affecting the formation of the two P10/P7 or the single P10/P7/P8 intermediates. Interactions between P7 and P8 in the absence of P10 or interactions between P10 and P8 in the absence of P7 could not be detected. These data indicate that purified P10, P7, and P8 interact in vitro in a manner completely in accord with the published assembly pathway and thus establish a system for further study of the regulation of the formation of this assembly intermediate in vitro.     

P63 and P73: P53 mimics, menaces and more

Inactivation of the tumour suppressor p53 is the most common defect in cancer cells. The discovery of its two close relatives, p63 and p73, was therefore both provocative and confounding. Were these new genes tumour suppressors, p53 regulators, or evolutionary spin-offs? Both oncogenic and tumour-suppressor properties have now been attributed to the p53 homologues, perhaps reflecting the complex, often contradictory, protein products encoded by these genes. p63 and p73 are further implicated in many p53-independent pathways, including stem-cell regeneration, neurogenesis and sensory processes.     

Autoradiographic localization of substance P receptors using I substance P

This paper describes a method for localization of substance P receptors in the rat central nervous system using ¹²⁵I labeled substance P in an autoradiographic procedure. Particularly high densities of substance P receptors were observed in the olfactory bulb, dentate gyrus, amygdala, superior colliculus, and locus coeruleus. Surprisingly low densities of substance P receptors were found in the substantia nigra pars reticulata, a region which contains high concentrations of substance P.     

Active site topologies of bacterial cytochromes P450101 (P450cam), P450108 (P450terp), and P450102 (P450BM-3). In situ rearrangement of their phenyl-iron complexes.

The reactions of cytochromes P450101 (P450cam), P450108 (P450terp), and P450102 (P450BM-3) with phenyldiazene result in the formation of phenyl-iron complexes with absorption maxima at 474-478 nm. Treatment of the cytochrome P450 complexes with K3Fe(CN)6 decreases the 474-478 nm absorbance and shifts the phenyl group from the iron to the porphyrin nitrogens. Acidification and extraction of the prosthetic group from each of the ferricyanide-treated enzymes yields a different mixture of the four possible N-phenylprotoporphyrin IX regioisomers. The ratios of the regioisomers with the phenyl ring on pyrrole rings B, A, C, and D (in order of elution from the high performance liquid chromatography column) are, respectively: cytochrome P450cam, 0:0:1:4; P450terp, 0:0:0:1; and P450BM-3, 2:10:2:1. The isomer ratio for recombinant cytochrome P450BM-3 without the cytochrome P450 reductase domain (2:9:2:1) shows that the reductase domain does not detectably perturb the active site topology of cytochrome P450BM-3. Potassium ions modulate the intensity of the spectrum of the phenyl-iron complex of cytochrome P450cam, but do not alter the N-phenyl isomer ratio. Computer graphics analysis of the crystal structure of the cytochrome P450cam phenyl-iron complex indicates that the active site of cytochrome P450cam is open above pyrrole ring D and, to a small extent, pyrrole ring C, in complete agreement with the observed N-phenylprotoporphyrin IX regioisomer pattern. The regioisomer ratios indicate that the active site of cytochrome P450terp is only open above pyrrole ring D, whereas that of cytochrome P450BM-3 is open to some extent above all the pyrrole rings but particularly above pyrrole ring A. The bacterial enzymes thus have topologies distinct from each other and from those of the mammalian enzymes so far investigated, which have active sites that are open to a comparable extent above pyrrole rings A and D.     

Purification and characterization of mouse protamines P1 and P2. Amino acid sequence of P2

Two mouse protamines, denoted as P1 and P2, have been purified directly from mature sperm nuclei and characterized as distinct polypeptide species. The complete primary structure of P2 was determined by peptide sequencing analyses. P1 and P2 were purified by a sequence of cation-exchange chromatography on Bio-Rex 70 and permeation chromatography on Bio-Gel P10, both in the presence of guanidine hydrochloride. Biochemical analyses demonstrate P1 has a molecular weight of 7400 and is characterized by the presence of arginine, cysteine, lysine, and tyrosine. By contrast, P2 is unusual in containing an abundance of arginine, histidine, lysine, and cysteine, but no tyrosine. The primary structure of P2 was determined from the sequencing of overlapping, high-pressure liquid chromatography purified peptides generated by thermolysin and endoproteinase Lys-C digestions and by chemical cleavage at each of four serine residues. Sequence analyses have demonstrated that P2, with a molecular weight of 8841, contains 62 amino acids, in the sequence NH2-Arg-Gly-His-His-His-His-Arg-His-Arg-Arg-Cys- Ser-Arg-Lys-Arg- Leu-His-Arg-Ile-His-Lys-Arg-Arg-Arg-Ser-Cys-Arg-Arg-Arg-Arg-Arg-His-Ser- Cys-Arg - His-Arg-Arg- Arg-His-Arg-Arg-Gly-Cys-Arg-Arg-Ser-Arg-Arg-Arg-Arg-Arg-Cys-Arg-Cys-Arg- Lys-Cys - Arg-Arg- His-His-COOH. Thus, the primary structure includes six clusters of arginine and histidine, distributed throughout the polypeptide, each ranging from five to eight amino acids in length. Sequence comparisons of mouse and human protamines by the Dayhoff program have revealed greater homology exists between human P2 and mouse P2 than within the P1 family from the two mammalian species.     

Determination of the P1', P2' and P3' subsite-specificity of factor Xa

Factor Xa is a central protease in the coagulation cascade and the target for many anticoagulant compounds currently under development. The preferences of the enzyme for substrates incorporating residues N-terminal to the cleavage site (P1, P2, etc.) have been elucidated, but little is known of its preferences for residues C-terminal to the cleavage site (P1', P2', etc.). The preferences of bovine factor Xa for substrate residues in the P1', P2' and P3' positions were mapped using fluorescence-quenched substrates. Bovine factor Xa, often used as a model for factor Xa, was most selective for the P2' position, less selective at the P1' position and almost completely non-selective at the P3' position. It appears that while the prime side subsites of factor Xa impose some selectivity towards substrates, the influence of these sites on factor Xa cleavage specificity is relatively low in comparison to related enzymes such as thrombin.     

An improved P2P lookup protocol model

With the development of the peer-to-peer (P2P) technology, a lot of lookup protocols have come out. Although we can benefit from different protocols separately, our research shows that if there exists a proper model, most of the seemingly different protocols can be classified to a same framework. Since technology is a kind of human behavior, we can set up the P2P lookup general model referring to some outcomes of cognitive psychology. In this paper, we firstly study the lookup model in cognitive psychology, then introduce the model into P2P search strategy, at last we give an improved Chord arithmetic based on the binary tree.     

Hybridization and recombination in the yeasts Pichia alni, P. bimundalis, P. finlandica, P. glucozyma, P. henricii, P. hostii, P. minuta var. nonfermentans, P. muscicola

A collection of genetic lines in 8 reproductively isolated Pichia species has been created. The above data have permitted realizing intraspecific hybridization and showing normal meiotic segregation of auxotrophic markers.     

Ribonuclease P

The gene coding for the RNA subunit of ribonuclease P (RNase P) is essential in all free-living organisms. The RNA subunit, itself, is an enzyme and, from its evolutionary tree, we can infer that it is a very ancient molecule. The specificity of this enzyme is that it cleaves other RNA molecules at the junction of single-stranded and the 5' end of double-stranded regions of RNA. One can speculate that this molecule was very useful in an ancient world in cleaving long pieces of RNA, which must have contained hairpin regions in it, into shorter molecules with the capability of different functions from the longer parent. Today, the specificity of the enzyme can be used in designing drug therapies.