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PubMed1982

The functional molecular weights of factor VIII activities in whole plasma as determined by electron irradiation.

Activities of the various components of the human factor VIII complex in citrated and heparinized human plasma have been determined following radiation inactivation of the plasma in a high energy electron beam at -135 degrees C in order to determine the molecular size of the functional units. In citrated and in heparinized plasma the functional size of VIII:C was 120,000 +/- 9,700 and 140,000 +/- 10,000, respectively. Taken together with previously published data, these results suggest that VIII:C exists in plasma as a dimer of noncovalently bonded functional subunits. The size of the functional unit of the ristocetin cofactor of the factor VIII complex was determined as being approximately 330,000 in both citrated and heparinized samples. Immunological assays for VIII:C (inhibitor neutralization assay), the VIII:C antigen, and the VIII:vWF-related antigen suggest that these may not be reliable under conditions favoring the activation and inactivation of factor VIII components by thrombin or other proteases.

Electrons↗
PubMed1999

Synthesis and Photophysical Properties of Porphyrin-Functionalized Molecular Clips.

Different clip-shaped receptor molecules functionalized at one side-wall with a porphyrin unit have been synthesized by a condensation involving a diamino glucoluril derivative and a porphyrin dione. A similar condensation reaction with a porphyrin tetraone resulted in porphyrin molecule with two receptor sites. The binding and photophysical properties of some of these porphyrin-receptor molecules are described.

Journal Article↗
PubMed2003

The protein tyrosine phosphatase PTP-Basophil/Basophil-like. Interacting proteins and molecular functions.

The protein tyrosine phosphatase PTP-Basophil (PTP-Bas) and its mouse homologue, PTP-Basophil-like (PTP-BL), are high molecular mass protein phosphatases consisting of a number of diverse protein-protein interaction modules. Several splicing variants of these phosphatases are known to exist thus demonstrating the complexity of these molecules. PTP-Bas/BL serves as a central scaffolding protein facilitating the assembly of a multiplicity of different proteins mainly via five different PDZ domains. Many of these interacting proteins are implicated in the regulation of the actin cytoskeleton. However, some proteins demonstrate a nuclear function of this protein tyrosine phosphatase. PTP-Bas is involved in the regulation of cell surface expression of the cell death receptor, Fas. Moreover, it is a negative regulator of ephrinB phosphorylation, a receptor playing an important role during development. The phosphorylation status of other proteins such as RIL, IkappaBalpha and beta-catenin can also be regulated by this phosphatase. Finally, PTP-BL has been shown to be involved in the regulation of cytokinesis, the last step in cell division. Although the precise molecular function of PTP-Bas/BL is still elusive, current data suggest clearly that PTP-Bas/BL belongs to the family of PDZ domain containing proteins involved in the regulation of the cytoskeleton and of intracellular vesicular transport processes.

Animals↗
PubMed1988

Evidence for distinct functional molecular sizes of carnitine palmitoyltransferases I and II in rat liver mitochondria.

1. Estimates of the functional sizes of the molecular species responsible for the overt (I) and latent (II) activities of carnitine palmitoyltransferase (CPT) in 48 h-starved rat liver mitochondria were obtained from radiation inactivation experiments. 2. The decay in the activity of total CPT and that of CPT II only (after inhibition of CPT I) was measured in mitochondrial samples exposed to different doses of high-energy ionizing radiation. 3. The decay curves obtained by plotting residual activity of total CPT as a logarithm function of irradiation dose suggested the contribution of more than one target towards total CPT activity. 4. By contrast, in mitochondria in which CPT I activity was approximately 95% inhibited, the activity of CPT decayed in a simple mono-exponential manner. Target-size analysis yielded an approximate Mr of 69,700 for this component (CPT II). 5. This information, as well as that on the relative non-irradiated activities of CPT I and CPT II, was used in graphical and statistical methods to obtain the parameters of the decay curve for CPT I. These analyses yielded an approximate Mr of 96,700 for CPT I.

Acyltransferases↗
PubMed2005

Ikaros-family proteins: in search of molecular functions during lymphocyte development.

The regulatory steps that lead to the differentiation of hematopoietic cells from a multipotential stem cell remain largely unknown. A beginning to the understanding of these steps has come from the study of DNA-binding proteins that are thought to regulate the expression of genes required for specific developmental events. Ikaros is the founding member of a small family of DNA-binding proteins required for lymphocyte development, but the members of this family differ from other key regulators of lymphopoiesis in that direct target genes have not been conclusively identified, and reasonable support has been presented for only a few potential targets. Therefore, the molecular mechanisms that Ikaros uses for regulating lymphocyte development remain largely unknown. Current data suggest that, in some instances, Ikaros may function as a typical transcription factor. However, recent results suggest that it may function more broadly, perhaps in the formation of silent and active chromatin structures. In this review, our current knowledge of the molecular functions of Ikaros will be discussed.

Animals↗
PubMed2000

Molecular evolution: dynamic combinatorial libraries, autocatalytic networks and the quest for molecular function.

The principles of Darwinian evolution have been explored in molecular systems such as autocatalytic networks and dynamic combinatorial libraries. Molecular evolution in such systems manifests itself as ligand or receptor amplification by selection. Research efforts exploring these concepts may provide a mechanism for the identification of novel catalysts, molecular receptors and bioactive molecules.

Catalysis↗
PubMed1987

Functional molecular size of trypsin inhibitors as determined by radiation inactivation analysis.

The molecular sizes of trypsin inhibitors obtained by radiation inactivation were investigated in relation to the functional domain size. The molecular weights obtained were 10,200 +/- 700 for ovomucoid, 17,800 +/- 400 for ovoinhibitor and 16,400 +/- 500 for soybean trypsin inhibitor. These values mostly agreed with the size of domain which has trypsin inhibitory activity, suggesting that the radiation inactivation analysis indicates the minimum functional domain size.

Animals↗
PubMed2002

Acute intermittent porphyria in Sweden. Molecular, functional and clinical consequences of some new mutations found in the porphobilinogen deaminase gene.

Acute intermittent porphyria (AIP) is an autosomal dominant disorder caused by a partial deficit of porphobilinogen deaminase (PBGD), the third of eight enzymes in the haem biosynthetic pathway. The overt disease is characterized by neuropsychiatric symptoms that are often triggered by exogenous factors such as certain drugs, stress, and alcohol. The aim of this work has been to identify the underlying genetic defect in each AIP-affected family in order to provide early counselling to assist in the avoidance of precipitating factors. The prevalence of AIP in Sweden is in the order of 1:10 000. The major mutation in Sweden, W198X, is due to a founder effect in the northern part of the country. This mutation, together with a further 11 mutations, have been reported previously. The present communication encompasses the great majority of AIP kindreds in Sweden and includes a further 27 mutations within the PBGD gene. This includes 14 completely new mutations, as well as 11 known mutations detected for the first time in Sweden. The majority of the mutations are located in exons 10 and 12 with fewer in exon 7. The clinical and biochemical outcomes in some patients are described. We also use the three-dimensional structure of the porphobilinogen deaminase enzyme to predict the possible molecular and functional consequences of the new Swedish missense and nonsense mutations.

Codon, Nonsense↗
PubMed2006

Directed ortho metallation of deep cavity cavitands: functionalizing molecular concavity.

Directed ortho metallation (DOM) processes have been used to functionalize the cavity and rim of title cavitand 1. The preorganization of the host resulted in a considerable reduction in the range of products produced. Thus, whereas sixty-nine products are possible from per-functionalization, only twelve were observed when the host was treated with three different alkyllithiums.

Journal Article↗
PubMed1992

[Function, molecular structure and gene expression of insulin-like growth factors ].

In this short review, gene structure, transcriptional pattern, biological activity, specific receptors and binding proteins for insulin-like growth factors (IGF: IGF I and IGF II) are explained. In spite of their close similarity in both gene and peptide structures, their receptors are completely distinct from each other in molecular structure and in signal transduction. Expression of IGF function in vivo is strongly restricted by plasma binding proteins.

Carrier Proteins↗
PubMed2006

Combining genetic and biochemical approaches to identify functional molecular contact points.

Protein-protein interactions are required for many viral and cellular functions and are potential targets for novel therapies. Here we detail a series of genetic and biochemical techniques used in combination to find an essential molecular contact point on the duck hepatitis B virus polymerase. These techniques include differential immunoprecipitation, mutagenesis and peptide competition. The strength of these techniques is their ability to identify contact points on intact proteins or protein complexes employing functional assays. This approach can be used to aid identification of putative binding sites on proteins and protein complexes which are resistant to characterization by other methods.

Journal Article↗
PubMed1992

[Function, molecular structure and gene expression of fibroblast growth factor (FGF/HBGF)].

The structure and function of members of the fibroblast growth factor (FGF) gene family and their receptors are reviewed. All the member of this gene family bind heparin, and therefore, are also called the as heparin-binding growth factor (HBGF). In this review, the structural features of FGF/HBGF are summarized first, and general features of the structure and function of their receptors are then described briefly. After biological effects of FGF/HBGF on adult-type tissues and cultured cells are reviewed, effects of FGF on the mesodermal induction in amphibian (Xenopus laevis) embryonic system are reviewed in more detail. Emphasis is given on the experiments with Xenopus animal cap assay system and also on the injection into Xenopus fertilized eggs of mRNA of dominant defect mutant of FGF receptor, which leads to the formation of embryos with abnormal axial mesoderm.

Animals↗
PubMed2006

Local flexibility in molecular function paradigm.

It is generally accepted that the functional activity of biological macromolecules requires tightly packed three-dimensional structures. Recent theoretical and experimental evidence indicates, however, the importance of molecular flexibility for the proper functioning of some proteins. We examined high resolution structures of proteins in various functional categories with respect to the secondary structure assessment. The latter was considered as a characteristic of the inherent flexibility of a polypeptide chain. We found that the proteins in functionally competent conformational states might be comprised of 20-70% flexible residues. For instance, proteins involved in gene regulation, e.g. transcription factors, are on average largely disordered molecules with over 60% of amino acids residing in "coiled" configurations. In contrast, oxygen transporters constitute a class of relatively rigid molecules with only 30% of residues being locally flexible. Phylogenic comparison of a large number of protein families with respect to the propagation of secondary structure illuminates the growing role of the local flexibility in organisms of greater complexity. Furthermore the local flexibility in protein molecules appears to be dependent on the molecular confinement and is essentially larger in extracellular proteins.

Arabidopsis↗
PubMed1992

[Function, molecular structure and gene expression of interferons].

Interferon is a key substance of the cytokine network, and is functioning not only as the virus inhibitory factor, but also as the factor for differentiation, development, and homeostasis of animals, including man. The molecular structure, induction mechanisms, interaction with receptor, and antiviral action mechanisms of IFN were reviewed. 1. Molecular structure of IFN IFNs are now divided into 4 types--alpha, beta, gamma, omega--according to antigenicities of IFN proteins, and to base sequence of their genes. The omega type was established officially on 1990 by the Nomenclature Committee of International Society for Interferon Research (ISIR). Also, the genes for HuIFNs were named as follows; HuIFN-A for HuIFN-alpha, HuIFN-B for HuIFN-beta, HuIFN-G for HuIFN-gamma, and HuIFN-W for HuIFN-omega. Nevertheless, the names of Type I IFN and Type II IFN are still valuable, since members of Type I IFN, alpha, beta, and omega, are similar in their molecular structures, and they share the common receptor (Type I IFN receptor), on the other hand, HuIFN-gamma (the only one member of Type II IFN) has different characteristics from the other IFNs, and binds to its specific receptor (Type II IFN receptor). However, it has been reported that both N-terminal and C-terminal of IFN protein of all types, participate in the binding of IFN to its receptor. 2. Induction mechanism of IFN. The factors, IRF-1 and IRF-2, were found to play an important role in IFN induction.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2005

7-Azaindolyl- and 2,2'-dipyridylamino-functionalized molecular stars with sixfold symmetry: self-assembly, luminescence, and coordination compounds.

Two novel star molecules functionalized with 7-azaindolyl and 2,2'-dipyridylamino groups have been synthesized. Both molecules possess a sixfold rotation symmetry. Molecule L1 is based on the hexaphenylbenzene core with the formula of hexa[p-(7-azaindolyl)phenyl]benzene, while molecule L2 is based on the hexakis(biphenyl)benzene core with the formula of hexa[p-(2,2'-dipyridylamino)biphenyl]benzene. Both compounds have been characterized by single-crystal X-ray diffraction analyses. Molecule L1 forms extended two-dimensional layered structure, while L2 forms interpenetrating columnar stacks in the solid state, as revealed by X-ray diffraction analyses. Nanowire structures based on columnar stacks through self-assembly of L2 on a graphite surface were revealed by an STM study. Molecules L1 and L2 are capable of binding to metal ions, resulting in unusual structural motifs. Two Ag(I) complexes with the formulae of [(AgNO(3))(2)(L1)] (1) and [(AgNO(3))(3)(L1)] (2) were isolated from the reactions of AgNO(3) with L1. Compound 1 displays extended intermolecular pi-pi stacking interactions that are responsible for its extended two-dimensional structure in the crystal lattice. Complex 2 has a "bowl" shape and forms polar stacks in the crystal lattice. A Cu(II) complex with the formula of [{Cu(NO(3))(2)}(6)(L 2)] (3) was isolated from the reaction of Cu(NO(3))(2) with compound L2. The six Cu(II) ions in 3 are chelated by the 2,2'-dipyridylamino groups of the star ligand L2. Intermolecular Cu-O (nitrate) bonds lead to the formation of an extended two-dimensional coordination network of 3. Both L1 and L2 are blue luminescent. Their interactions with Ag(I) or Cu(II) cause drastic quenching of emission. In addition, the luminescence of L1 and L2 is sensitive to the presence of protons, which cause a reduction of emission intensity and a red shift of the emission energy.

Journal Article↗
PubMed2006

Modulating molecular functions of p53 with small molecules.

Association of the human tumor suppressor p53 with many human cancers makes it a valuable therapeutic target. Stress-induced molecular interactions of p53 with other effector proteins are immensely intertwined with regulation of its functions in orchestrating a wide array of cellular responses, thereby defying analysis of the underlying molecular mechanisms with conventional molecular and cellular biology methods. Recent discoveries of small molecules that can selectively modulate the molecular interactions of p53 offer promising opportunities to address the challenge of dissecting these complex mechanisms and increase the hope for pharmacological control of p53 for clinical benefits of cancer patients.

Amino Acid Sequence↗
PubMed2006

Molecular functions of nuclear actin in transcription.

Actin is not only a major cytoskeletal component in all eukaryotic cells but also a nuclear protein that plays a role in gene transcription. We put together data from in vitro and in vivo experiments that begin to provide insights into the molecular mechanisms by which actin functions in transcription. Recent studies performed in vitro have suggested that actin, in direct contact with the transcription apparatus, is required in an early step of transcription that is common to all three eukaryotic RNA polymerases. In addition, there is evidence from in vivo studies that actin is involved in the transcription elongation of class II genes. In this case, actin is bound to a specific subset of premessenger RNA binding proteins, and the actin-messenger RNP complex may constitute a molecular platform for recruitment of histone-modifying enzymes. We discuss a general model for actin in RNA polymerase II transcription whereby actin works as a conformational switch in conjunction with specific adaptors to facilitate the remodeling of large macromolecular assemblies at the promoter and along the active gene.

Actins↗