eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31273
ELUCIDATION OF pK VALUES FOR ACTIVE
SITE OF HORSERADISH PEROXIDASE AND
BINDING STUDY OF INTERACTION WITH
N-PHENYL BENZHYDROXAMIC ACID USING A
SPECIAL DIFFERENCE
SPECTROPHOTOMETRIC TECHNIQUE
The binding behavior of a competitive inhibitor, N-phenylbenzhydroxamic acid
(BHA) against horseradish peroxidase (HRP) was studied in order to understand and
predict the interaction mechanism of hydrogen donors with the enzyme. The
dissociation constants of the complexes of HRP-BHA, HRP-donor and HRP-BHA-azide were estimated at specified conditions by difference spectroscopy. The binding site of BHA and that of hydrogen donor were also detected by spectroscopic titration of HRP in the presence of BHA and specific amino acid modifiers. A histidine binding site with pK = 6.40 was detected for the binding of BHA. On the other hand, activity-pH measurements showed that the maximum interaction of BHA with HRP occurs at a minimum point of activity at pH=6.40. The catalytic behavior of His 42 in the kinetic mechanism of enzyme action was also discussed
https://jsciences.ut.ac.ir/article_31273_3ce4cb242290db406affa82736a3520a.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31274
PRODUCTION, RELEASE AND THERMAL
CHARACTERIZATION OF CELLULOLYTIC
ENZYME FROM CELLULOMONAS sp. STRAIN "0"
Cellulase production by a Cellulomonas sp., isolated in 1985 from forest humus
soil along the border of the Caspian Sea in Iran, was investigated. This strain secreted
endo-and exo-cellulases in the culture medium, but some of the enzymes produced
remained cell membrane bound. Cell bound enzymes were released by various
treatments. The highest amount of endo-glucanase (up to 95%) and exo-glucanase
(62%) was released when the cells were treated with 1% Tween 80 for 300 and 60
minutes, respectively. No extracellular or cell membrane bound ?-glucosidase was
obtained. Optimum temperature for the endo-glucanase and exo-glucanase activities
was 50°C and optimum pH was 7 for both enzymes. Thermal stability of enzymes was
measured at 30 to 50°C and was compared with that of endo- and exo-glucanses from
mesophilic fungi such as Neurospora crassa, Trichoderma viri& and Pencillium
funiculosum. It was found that the thermal stability of endo- and exo-glucanases from
Cellulomntas sp. strain "0"w as the same as that of fungal enzymes up to 37?C,
however, at higher temperatures these enzymes lost their activities faster than the
fungal cellulases
https://jsciences.ut.ac.ir/article_31274_b36a2845e7e5d37b094f988e5b92cedb.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31275
A SIMPLE MODEL FOR THE ESTIMATION OF
DIELECTRIC CONSTANTS OF BINARY
SOLVENT MIXTURES
A simple and reliable method for quick estimation of the dielectric constant of a
binary solvent mixture is proposed. The validity of the proposed method has been
tested for a broad range of binary solvent mixtures
https://jsciences.ut.ac.ir/article_31275_a36b1d6d521e9da08ccd4e4f509cb5ce.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31276
DIFFERENTIAL PULSE POLAROGRAPHIC
DETERMINATION OF OSMIUM BY CATALYSIS
OF PYROGALLOL-RED BROMATE REACTION
A highly sensitive differential pulse polarographic (DPP) method has been
developed for the determination of trace amounts of osmium, based on the catalytic effect of osmium (VIII) on the oxidation of pyrogallol red (PGR) by sodium bromate at pH 7.00 and 25.0 0.1 ? C. The reaction rate was monitored by measuring the differential pulse cathodic current of the oxidation product of PGR and bromate. Various parameters such as the effect of pH, reagents concentrations, time, temperature and interference of a number of cations and anions on the estimation of osmium have been studied to optimize the conditions for determination of osmium. The concentration of osmium in the range of 0.1- 300 ng ml has been determined. The limit of detection was 0.02 ng ml . The precision and accuracy of the method are reported
https://jsciences.ut.ac.ir/article_31276_b853e88c699654fa0842a3fa194826e5.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31277
SYNTHESIS OF 1,2,4-TRIAZINO [3,4-C] [I ,2,4]
BENZOTRIAZINE, A NOVEL HETEROCYCLIC
SYSTEM
3-Mercapto-1,2,4 benzotriazine (1) was methylated by methyl iodide in the
presence of base to afford 1,2-dihydro-3-methyhercapto-1, 2,4 benzotriazine (2).
The latter was reacted with hydrazine hydrate to give the corresponding 3-hydrazine
derivative (3). Compound (3) on condensation with phenacyl bromide gave 3-
phenacyl hydrazino l,2,4-benzotriazine (4). PPA cyclization of the ketone (4)
yielded lH, 2H, 10H-4-phenyl-triazino [3,4-c]- 1,2,4-benzotriazine (5). Triazino
benzotriazine (5) is a novel heterocyclic system and is reported for the first time.
https://jsciences.ut.ac.ir/article_31277_bcdaca4911a22c0b00f6b3f3ab360f56.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31278
EXTENSION OF LINEAR ISOTHERM
REGULARITY TO LOWER DENSITY RANGE
The general equation of state which was found for dense fluids, both compressed
liquids and dense supercritical fluids, namely "Linear Isotherm Regularity," is
extended to the lower density range, specifically for densities lower than the Boyle
density. This new equation of state which is called "ELIR" is shown to be compatible
with the equations of state based on statistical-mechanical theory, although ELIR
gives a more accurate density at high pressures. This equation of state has been tested
with experimental data for different fluids (Ar,N , O , CO, CH , C H , CH 0H ,H )
for both vapor and compressed liquid phases. The ELIR is able to predict the critical isotherm and also both of the coexistence phases at equilibrium can be expressed by a single ELIR equation of state
https://jsciences.ut.ac.ir/article_31278_65cddde575a7fdbfb821f6e53f638961.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31279
PALYNOSTRATIGRAPHY AND
PACAIEOGEOGRAPHY OF EARLY PEFIMM
STRATA IN THE ZAGROS BASIN, SOUTHEAST SOUTHWEST IRAN
A totall of 500 Early Permian samples from the Chal-i-Sheh Formation in the
Zagros Basin were examined palynollogically in order to determine the stratigraphical
age of the formation and to assess the palaeogeopaphicd relatianships of this basin
to the Southern and Northern Hemispheres during the Early Permian. Fifty-eight taxa
were recorded including 46 pollen, 10 spore and 2 acritarch species, which permitted
the establishment of the age of the formation. Quantitatively, pollen contributed 98
percent, spores 1.5 percent, and acritarchs 0.5 percent of the total assemblages. The
high relative percentage of gymospermous pollen taxa suggests a relatively cold
condition which was in favor of gymnospernous plants at the beginning of the Early
Permian, Comparison of the taxa recorded from the Early Permian strata of the Zagros Basin with those reported from other parts of the world indicates that the Zagros Basin was part of the Gondwanan Supercontinent located on the southern shore of Tethys sea during the Permian period
https://jsciences.ut.ac.ir/article_31279_d277221cd1cb502f1bd8bf25298efa1f.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31280
FOCAL POINT AND FOCAL K-PLANE
This paper deals with the basic notions of k-tautimmersions . These notions come
from two special cases; that is, tight and taut immersions. Tight and taut based on high and distance functions respectively and their basic notions are normal bundle, endpoint map, focal point, critical normal. We generalize hight and distance functions to cylindrical function and define basic notions of k-taut immersions such as k-plane
normal bundle , end k-plane map, focal k-plane, and critical k-plane normal. Then we
prove index theorems for cylindrical function similar to the standard index theorems
of distance function . In this way, the key point is the relation between focal point and focal k-plane
https://jsciences.ut.ac.ir/article_31280_47f5e4861ece5ea6db8a95854d949633.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31281
FLOWS AND UNIVERSAL
COMPACTIFICATIONS
The main purpose of this paper is to establish a relation between universality of
certain P-compactifications of a semitopological semigroup and their corresponding
enveloping semigroups. In particular, we show that if we take P to be the property that the enveloping semigroup of a compactification of a semitopological semigroup s is left simple, a group, or the trivial singleton semigroup, then the universal P- compactification of S would be the distal, the right simple, or the right zero
compactification , respectively
https://jsciences.ut.ac.ir/article_31281_1c5fe00eaa938fea7fc99272815e62ec.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31282
EFFECT OF FUSION REACTION PRODUCTS
HEATING ON THE VOLUME IGNITION OF DT
AND D3He FUEL PELLETS
Laser fusion simulations are carried out for DT and D- He pellets by using a
hydrodynamic code including heating from all charged reaction products and
neutrons. It is shown that the inclusion of the side reactions and heating from all
reaction products in the fuel pellets have an appreciable effect on the plasma
temperature, the ICF drive energy requirement, fusion gain and the ignition
conditions. The total input energy is decreased and the burn efficiency and total gain
are increased compared to the results of simple volume ignition calculations
https://jsciences.ut.ac.ir/article_31282_50bb65b8ba7e2c4193b57e291f621a4d.pdf
eng
University of Tehran
Journal of Sciences, Islamic Republic of Iran
1016-1104
2345-6914
1997-12-01
8
4
31283
THE THEORY OF PHOTOTHERMAL LENSING
SPECTROSCOPY
A general theoretical description of dual-beam photothermallensing spectroscopy
is given. The results are valid for most general conditions, that is, for flowing as well
as stationary media, for optically thick as well as optically thin media, and also for any transverse modes of incident pump beams
https://jsciences.ut.ac.ir/article_31283_5df7b0d31453075b13d5a35c74d9186e.pdf