Calculation of harmonic force constants,vibrational frequencies and integrated intensities of some organic molecules using the MINDO—Forces method

The harmonic force constants, vibrational frequencies and integrated intensity ratios of CH₂, H₂O, CH₂O, C₂H₂, CO₂, HCN, CH₃, CH₄, and C₂H₄ have been calculated using the MINDO—FORCES program and the Pulay method for the calculation of the molecular force constants. The results obtained are in general quite satisfactory when compared with available literature values. The results are, however, not as satisfactory in case of molecules containing heteroatoms, due to the neglect of some dipolar repulsion integrals for the heteroatoms by the MINDO/3 method. Calculated integrated intensities for CH₃ and C₂H₄ agree well with experimental results. The calculated integrated intensities for other molecules are obtained for the first time and no comparison with published data is therefore possible.Part of the M.Sc. Thesis of K. H. A. 1978.     

Synthesis of selective inhibitors against V. cholerae sialidase and human cytosolic sialidase NEU2

Sialidases or neuraminidases catalyze the hydrolysis of terminal sialic acid residues from sialyl oligosaccharides and glycoconjugates. Despite successes in developing potent inhibitors specifically against influenza virus neuraminidases, the progress in designing and synthesizing selective inhibitors against bacterial and human sialidases has been slow. Guided by sialidase substrate specificity studies and sialidase crystal structural analysis, a number of 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (DANA or Neu5Ac2en) analogues with modifications at C9 or at both C5 and C9 were synthesized. Inhibition studies of various bacterial sialidases and human cytosolic sialidase NEU2 revealed that Neu5Gc9N(3)2en and Neu5AcN(3)9N(3)2en are selective inhibitors against V. cholerae sialidase and human NEU2, respectively.     

Efficient one-pot multienzyme synthesis of UDP-sugars using a promiscuous UDP-sugar pyrophosphorylase from Bifidobacterium longum (BLUSP)

A promiscuous UDP-sugar pyrophosphorylase (BLUSP) was cloned from Bifidobacterium longum strain ATCC55813 and used efficiently with a Pasteurella multocida inorganic pyrophosphatase (PmPpA) with or without a monosaccharide 1-kinase for one-pot multienzyme synthesis of UDP-galactose, UDP-glucose, UDP-mannose, and their derivatives. Further chemical diversification of a UDP-mannose derivative resulted in the formation of UDP-N-acetylmannosamine.     

Inversion des aromatisch-substituierten Stickstoffs

Zusammenfassung Die Inversionsbarrieren aromatischer Amine wurde mittels der MINDO/1-Methode berechnet. Die Resultate wurden mit denen eines einfachen PMO-Verfahrens verglichen, wobei sich befriedigende Übereinstimmung ergab. Die Dipolmomente und Ladungsdichten werden angegeben und mit den entsprechenden Werten der planaren Konformation verglichen. Schließlich werden Geometrie und Isomerie von p-Phenylen-diamin diskutiert.

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The inversion of aromatic-substituted nitrogen

Inversionsbarriers of aromatic amines are calculated using the MINDO/1 SCF-MO-method. The obtained values are compared with those resulting from a simple PMO-treatment, showing a good agreement with the latter. Dipolmoments and chargedensities of the amines are reported and compared with those of the planar conformation. The geometry and isomerism of p-phenylene-diamin is studied in the means of the previous method.

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Résumé Les barrières d'inversion des amines aromatiques sont calculées avec la méthode MINDO/1 SCF MO. Les valeurs obtenues sont comparées avec celles résultant d'un simple traitement PMO et sont en bon accord avec celles-ci. Les moments dipolaires et les densités de charge des amines sont comparés à ceux de la conformation plane. Etude de la géométrie et de l'isomérie de la p-phénylènediamine.

     

Specific Targeting of PEGylated Liposomal Doxorubicin (Doxil®) to Tumour Cells Using a Novel TIMP3 Peptide

Doxorubicin is a cytotoxic anthracycline derivative that has been used as a chemotherapeutic in many different forms of human cancer with some success. However, doxorubicin treatment has several side-effects, the most serious of which is cardiomyopathy, that can be fatal. Doxorubicin encapsulation in PEGylated liposomes (Doxil^®) has been shown to increase tumour localisation and decrease cardiotoxicity. Conversely, the stability of such liposomes also leads to increased circulation times and accumulation in the skin, resulting in palmar planter erythrodysesthesia, while also limiting release of the drug at the tumour site. Specific targeting of such liposomes to tumour cells has been attempted using various receptor-specific peptides and antibodies. However, targeting a single epitope limits the likely number of tumour targets and increases the risk of tumour resistance through mutation. In this report, Doxil^® was coupled to peptide sequence p700 derived from tissue inhibitor of metalloproteinase 3. This Doxil^® -P700 complex results in an approximately 100-fold increase in drug uptake, relative to Doxil^® alone, by both mouse and human breast cancer cells and immortalised vascular cells resulting in an increase in cytotoxicity. Using p700 to target liposomes in this way may enable specific delivery of doxorubicin or other drugs to a broad range of cancers.     

The rotation barrier of the cyclopropylcarbinylcation

The rotation barrier of the cyclopropylcarbinyl-cation has been calculated by the MINDO/2 method.     

Finite edge-transitive oriented graphs of valency four with cyclic normal quotients

We study finite four-valent graphs \(\Gamma \) admitting an edge-transitive group G of automorphisms such that G determines and preserves an edge-orientation on \(\Gamma \), and such that at least one G-normal quotient is a cycle (a quotient modulo the orbits of a normal subgroup of G). We show, on the one hand, that the number of distinct cyclic G-normal quotients can be unboundedly large. On the other hand, existence of independent cyclic G-normal quotients (that is, they are not extendable to a common cyclic G-normal quotient) places severe restrictions on the graph \(\Gamma \) and we classify all examples. We show there are five infinite families of such pairs \((\Gamma ,G)\) and in particular that all such graphs have at least one normal quotient which is an unoriented cycle. We compare this new approach with existing treatments for the sub-class of weak metacirculant graphs with these properties, finding that only two infinite families of examples occur in common from both analyses. Several open problems are posed.     

Efficient chemoenzymatic synthesis of sialyl Tn-antigens and derivatives

An N-terminal and C-terminal truncated recombinant α2-6-sialyltransferase cloned from Photobacterium sp. JH-ISH-224, Psp2,6ST(15-501)-His(6), was shown to be an efficient catalyst for one-pot three-enzyme synthesis of sialyl Tn (STn) antigens and derivatives containing natural and non-natural sialic acid forms.     

Center-like subsets in rings with derivations or endomorphisms

Our purpose in this paper is to show that certain subsets, defined by commutativity conditions involving derivations or endomorphisms, coincide with the center in prime rings. Moreover, we provide examples to show that the assumed restrictions cannot be relaxed.