H/ complex

Group of transmembrane proteins engaged in the presentation of small peptide fragments to T-cells. Two classes of Major histocompatibility complex (MHC) molecules exist both of which are encoded by a highly polymorphic gene cluster. MHC class I and class II proteins present peptide fragments to CD8+ and CD4+ T-cells, respectively. The human MHC is also known as HLA, the murine MHC as H-2 complex. 

The calculated thermodynamic parameters in Table X are for 150 °C, a value close to typical operating temperatures, and without pressure corrections, there is no H2 and both alkane and alkene could be at unit concentration. The bottom part of the table is the same as Table VI. The free-energy profile of the transfer reaction mechanism is shown in Fig. 4. In the first step of the mechanism (IVR), sacrificial alkene (in this case ethylene) was bound to the (L)Ir(H)2 complex 4 to form an olefin complex 7. As mentioned above, the forward reaction of this step has no... 

Doherty, P.C. and Zinkemagel, R.M. (1975) Enhanced immunological surveillance in mice heterozygous at the H-2 complex. Nature 256, 50-52. 

The Schiff base a-N-methyl-S-methyl-P-iV-(2-hydroxyphenyl)methylenedithiocar-bazate (144) loses a proton on co-ordination to nickel(n) to function as a terdentate NOS donor in [Ni(L - H)X](X = Cl, Br, or NCS), all planar diamagnetic complexes. Similarly the Ni(L — H)2 complex is octahedral //eff = 3.10 BM.601... 

In this case, the first reaction (reaction R-4.26) is not reversible. Hydrogen inhibition is attributed to the formation of the C(H)2 complex. The reaction rate becomes... 

The cis- and rrans-[Pd(nucl-H+)2] complexes can be prepared only when a nucleoside containing an easily ionizable imino proton, such as inosine or guanosine, is used. The pK values of the imino proton of these bases fall in the range... 

Over the last two decades, Wilkinson complex and related phosphine complexes of rhodium(I) have been used in numerous reactions for synthetic purposes, such as in the hydrosilylation of styrene and vinylcyclo-propene to yield ring-opening products of vinylamines. The [ (dippe)Rh 2(/u.-H)2] complex [where dippe = l,2-bis(diisopropylphosphino)ethane] is active in the hydrosilylation of olefins by diphenylsilane (4). Rhodium complexes were extremely favorable catalysts for dehydrogenative silylation of alkenes and divinyldiorganosilanes (4,13). 

Table 3.3 Genetic traits under control of the H-2 complex ...

Important questions about the H-2 complex which are currently under very active investigation concern the number of discrete genes, their specific functions, the nature of their products, and whether some of the different traits which have been described may reflect different manifestations of the action of the same gene. In the following sections we will briefly consider the current state of understanding of these problems. 

The I (Immune response) region of the H-2 complex was initially defined by the studies of McDevitt and co-workers on the Ir-1 genes. These immune response genes are reviewed in detail by Benacerraf in Chapter 4 of this volume. Therefore, we will simply summarize their principal features. 

To date, H-2-associated differences in immune responses to more than 25 different antigens have been described. In the majority of cases, these involve quantitative differences in the level of specific antibody produced in the secondary response to a given antigen. Each of these response differences has been demonstrated to be under the control of a single, major genetic determinant which is linked to the H-2 complex. Analyses of intra-H-2 recombinants have mapped most of these response differences to the interval between the H-2K and Ss loci, i.e. the I region . 

Another very interesting and biologically very important phenomenon associated with the H-2 complex, and probably controlled by the I region, is the difference among H-2 haplotypes in susceptibility to certain oncogenic viruses. This was first described by Lilly, who found that susceptibility to in-... 

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