Two metabolites ( 1 , and 2 ) ) of p-aminobenzoic acid ( PABA ) which act as cofactors for the hydroxylation of aniline by acid-fast bacteria are biosynthesized from Aj .
The 7 carbons of PABA are incorporated directly into metabolite 2 ( ( as shown with both ring-labeled and carboxy-labeled Af ) .
Thirty-five of the 36 carbon atoms arise from Aj .
All 28 carbons of metabolite 1 ( ( a product of mild acid hydrolysis of 2 ) arise from Aj .
Metabolite 1 , isolated from the medium , however , showed a lower specific activity , which indicates endogenous synthesis of this metabolite .
Vigorous acid hydrolysis of metabolite 1 , destroyed the biological activity of the compound and liberated two aryl amines .
Fragment A has been obtained in crystalline form as a dioxalate salt and free base .
Preliminary evidence tentatively indicates that the molecule ( metabolite 1 ) ) is cleaved at a secondary amide bond .
( N. H. Sloane ; ;
chemical studies are being pursued with the cooperation of K.G. Untch .
) studies on esterases
-- Research on esterases in mammalian sera was continued .
One of the most interesting findings was the extreme sensitivity of plasma arylesterases to rare earth ions .
The inhibition of the enzyme by very low concentrations of lanthanum ion is probably the strongest known biological effect of rare earth salts .
Various metal ions have been found to protect plasma arylesterase against inactivation by urea and guanidine .
The effects can be related to the structure of this enzyme .
The non-identity of serum and red blood cell arylesterase was also established .
Furthermore , the hydrolysis of paraoxon was studied in mammalian sera , and it was found that it is hydrolyzed by albumin ( or a factor attached to it ) in addition to arylesterase .
Selective inhibitors can distinguish the two activities .
Investigations on the acceleration of human plasma cholinesterase were carried further .
( E. G. Erdos , L. E. Boggs , C. D. Mackey ) biophysical studies on modified fibrous proteins
-- Electron-microscopical and physical-chemical methods were used to demonstrate the renaturation of heat-denatured collagen and ribonucleic acid .
( R. V. Rice )
A method was devised for extracting and purifying soluble earthworm collagen ( EWC ) .
It was observed that EWC macromolecules are the same diameter ( 15 a. ) but much longer ( up to several microns ) than vertebrate tropocollagen .
This unusual collagen also was shown to undergo a reversible thermal phase transformation .
( R. V. Rice , M. D. Maser ) studies on peptides and peptidases
-- This investigation involved several aspects .
Substance Z , an active urinary peptide , was purified by extraction in organic solvents and repeated column chromatography ; ;
high-voltage electrophoresis and paper chromatography were used in preliminary structural studies ; ;
pharmacological effects in vitro on isolated surviving organs and in vivo on blood pressure were assayed ; ;
special equipment required for registering respiration and for recording the contraction of smooth muscles under various conditions was developed by the Instruments Section ( Victor Jackman , W. C. Barnes , J. F. Reiss ) ; ;
and enzymes which terminate the action of peptides such as bradykinin and perhaps Substance Z were studied .
Experiments are in progress to develop ultraviolet spectrophotometric techniques for assaying these enzymes and for studying their sensitivity to metal ions .
( E. G. Erdos , C. D. Mackey , A. G. Renfrew , W. B. Severs , E. M. Sloane ) seed proteins
-- In a physiochemical study of seed proteins , the globulins of the Brazil nut have been investigated .
In addition to the known principal globulin , excelsin , three other ultracentrifugally distinct components have been observed .
A water-soluble protein of quite low molecular weight ( ca. 10,000 ) has also been found in this system and partly characterized .
( E. F. Casassa , H. J. Notarius )
continuum mechanics and viscoelasticity
theory of non-newtonian fluids
-- On the basis of a differentiability assumption in function space , it is possible to prove that , for materials having the property that the stress is given by a functional of the history of the deformation gradients , the classical theory of infinitesimal viscoelasticity is valid when the deformation has been infinitesimal for all times in the past .
By strengthening the differentiability assumption , it has been possible to derive second and higher order theories of viscoelasticity .
In the second-order theory , one of the normal stress differences can be calculated from the first-order stress relaxation function .
( B. D. Coleman with Walter Noll , Department of Mathematics , Carnegie Institute of Technology ) viscoelastic measurements
-- An extensive series of measurements was made on a high-density polyethylene in a torsion pendulum instrument using forced sinusoidal oscillation , free vibration , and creep measurements over the temperature range of Af to 80-degrees-C .
As many as seven decades of the time scale were thus covered isothermally .
The simple time-temperature equivalence valid for many amorphous systems did not hold here .
It was possible , however , to decompose the compliance into a sum of a frequency-independent component and two viscoelastic mechanisms , each compatible with the Boltzmann superposition principle and with a consistent set of time-temperature equivalence factors .
( Hershel Markovitz , D.J. Plazek , Haruo Nakayasu )
trace elements in tektites , meteorites , and related materials
-- The results of microanalysis of tektites ( natural glasses of unknown origin ) for gallium and germanium have shown that these glasses are probably produced from terrestrial ( or less likely from lunar ) matter by impact of a celestial body .
The gallium / germanium ratio is higher than that for ordinary igneous , metamorphic , or sedimentary matter as a result of selective volatilization of the components of the tektite .
Gallium oxide is less volatile than silica ( the main constituent of tektites ) and germanium oxide is more volatile .
Australites ( tektites from Australia ) give the appearance of a second melting .
In conformity with this conclusion a higher trace gallium content was found in the portion ( flange ) that has undergone a second melting .
The silicate fractions of stony meteorites show gallium / germanium ratios similar to those of tektites because they too have undergone melting at some point in their histories .
Libyan Desert silica-glass , another natural glass , is composed of nearly pure silica and has the same trace germanium content as sands in the area .
The gallium content , however , has been enhanced five-fold .
This glass is probably formed from Libyan Desert sands by comet or stony-meteorite impact .
Nickel-iron meteorites with sufficient kinetic energy to produce large terrestrial explosion craters may nevertheless melt only small quantities of material .
Most of the impact energy is spent in crushing and fragmentation .
When rapid quenching follows melting , impact glasses may result .
These always contain metallic inclusions .
Impact glasses not containing elemental nickel-iron may have been produced by stony meteorites or comets .
No meteorites have ever been recovered from paleoexplosion craters , and recent craters containing impact glass have all been produced by metallic meteorites with the exception of Aouelloul crater , Adrar , Western Sahara Desert .
This crater contains impact glass with no metallic inclusions and no meteoritic material has been recovered .
( A. J. Cohen , John Anania )
Preparation of a coordination compound is often accomplished by the simple method of reacting a metal salt with a ligand in a suitable solvent such as an alcohol .
By applying this general principle , a great number of complex compounds of osmium , ruthenium , iridium , and rhenium , with triphenylphosphine , triphenylarsine , and triphenylstibine have been obtained in this laboratory during the past few years .
( Lauri Vaska , E. M. Sloane , J. W. DiLuzio ) In the absence of direct evidence to the contrary , decomposition of solvent alcohol and coordination of its fragments to the metal were not considered , following the above heretofore-accepted assumption in preparative coordination chemistry .
Recent work with radiocarbon and deuterated alcohols as solvents , however , has given evidence that metal-hydrido and carbonyl complexes may be readily formed by reaction with alcohol in some of these systems .
Some of the previously reported compounds have thus been reformulated and a series of new hydrido and carbonyl compounds discovered , the more representative examples being Af , Af , Af , Af and Af ( Af ) .
The coordination complexes formed by transition metals with primary and secondary phosphines and arsines are being investigated ( R. G. Hayter ) .
Particular interest is directed towards the condensation of these ligands with metal halides to form substituted phosphide or arside complexes .
During the past year , these ligands have yielded some unusual five-coordinate complexes of nickel ( 2 ) and some interesting binuclear phosphorus-bridged complexes of palladium ( 2 ) ( see figure ) , as well as new compounds of the well-known type Af .
The structures , properties , and reactions of these compounds are being studied .
In another study chromium-substituted aluminum oxyhydroxides and related species , prepared homogeneously by high-temperature hydrolysis , are being characterized and investigated spectrally in the ultraviolet region with a view to identification and semiquantitative estimation of the phases formed under varying preparative conditions .
( J. A. Laswick , N. L. Heatwole )
structure and properties of macromolecules
elasticity of macromolecular networks
-- The theory of elasticity of Gaussian networks has been developed on a more general basis and the equations of state relating variables of pressure , volume , temperature , stress and strain have been precisely formulated .
Simple elongation has been treated in detail .
The various stress-temperature coefficients for constancy of volume and strain , constancy of pressure and strain , and constancy of pressure and length have been interrelated .
The dilation accompanying elongation and the simultaneously developed anisotropy of compressibility have been related to the elongation .
In continuation of these theoretical studies , a more precise elucidation of the effects of imperfections in network structure is sought .
( P. J. Flory , C. A. J. Hoeve ) chain conformations of polymeric chains
-- Recent theoretical work to calculate the dimensions of polymeric chains by Volkenstein and Lifson has been extended to include more general types of chains .
The mean-square end-to-end distance of the polyisobutylene chain has been calculated in reasonable agreement with values deduced from viscosity data .
These studies are being extended to different polymers to increase our knowledge about the hindrances to rotation around chain bonds .
( C. A. J. Hoeve , A. A. Blumberg ) crystallization in polymers and copolymers
-- The crystallization of copolymers comprising Af units interspersed with a minor percentage of Af is limited by the inability of the crystal lattice characteristic of the former to accommodate the bulky side group of the latter .
Only uninterrupted sequences of the former are eligible for formation of crystallites .
Limitations on the lengths of these sequences diminish the stability of the comparatively short crystallites which can be formed , and this is reflected in a broadening of the melting range .
( Robert Chiang , J. B. Jackson , P. J. Flory ) Carefully executed melting studies on this system ( M. J. Richardson ) permit quantitative estimation of the instability engendered by reduced crystallite length .
The complex morphology of polycrystalline homopolymers is necessarily dependent on the same factor .
Hence , the present studies offer a possible basis for interpretations in the latter field .
Contraction of muscle
-- Glycerinated muscle , in the presence of the physiological agent ( ATP ) responsible for delivering energy to the mechanochemically active proteins of muscle , has been shown to undergo a contraction which is highly sensitive both to temperature and to solvent composition in mixtures of alcohols and water .
Experiments carried out over long periods of time in order to allow establishment of a steady state have shown that the onset of contraction and its completion are confined to an interval of several degrees Centigrade and to a concentration range of only several per cent .
The contraction therefore partakes of the character of a phase transition .
While ATP appears to be necessary for the occurrence of contraction , its presence and enzymatic hydrolysis of it by the muscle protein myosin are not the only criteria for contraction .
( C. A. J. Hoeve , P. J. Flory ) anionic Polymerization
-- One of the principal aims of anionic polymerization techniques is the synthesis of polymers of extremely narrow molecular weight distribution .
A simple process for the preparation of nearly monodisperse polystyrene of predictable molecular weight has been developed .
The preparation of such products is not new , but the systems heretofore employed in polymerizations have commanded considerable experimental skill and starting materials of a high purity .
In the new process impurities present in the solvent ( benzene ) , the monomer , and in the reaction system which would cause deactivation of propagation centers , are rendered inactive prior to polymerization by gradual addition of initiator , a mixture of butyl-lithium and telomeric styryl-lithium , at a temperature low enough to suppress chain growth .
Upon completion of the purging step , additional initiator appropriate for the molecular weight of the sample desired is added , and the system is then warmed to the polymerization temperature , at which the reaction is allowed to go to completion .
The predictability of the molecular weights was found to be within 10% for the polymers prepared , with Af ratios less than 1.1 .
Contrary to observations with ethers , no apparent change of the reactivity of the chain ends takes place over considerable periods of time in benzene as solvent .