molecular weight characteristic
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Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2079
Author(s):  
Carlos Molina-Ramírez ◽  
Paulina Mazo ◽  
Robin Zuluaga ◽  
Piedad Gañán ◽  
Juan Álvarez-Caballero

Scales of Prochilodus magdalenae, a Colombian endemic fish species, were used to obtain chitosan for application as an antibacterial agent integrated into starch-based films. Analysis of its composition during the demineralization and deproteinization process indicated that minerals and protein were both removed successfully. At this point, mild conditions for the deacetylation process were employed, namely, 2, 4, and 6 wt.% NaOH at room temperature for 16 h. Chitosan processed under 2 wt.% NaOH had low molecular weight, with the lowest value of 107.18 ± 24.99 kDa, which was closely related to its antibacterial activity. Finally, this chitosan was integrated into a banana starch-based film, and its antibacterial activity was assayed in Escherichia coli and Staphylococcus aureus cultures, with positive results in the former culture, especially due to the low-molecular-weight characteristic of chitosan.


1991 ◽  
Vol 260 (6) ◽  
pp. R1229-R1234 ◽  
Author(s):  
P. Soppela ◽  
M. Nieminen ◽  
S. Saarela ◽  
J. S. Keith ◽  
J. N. Morrison ◽  
...  

Reindeer inhabit a severe arctic or subarctic environment, with the young born in early spring under adverse weather conditions. The extreme northern climate imposes a major thermal challenge to the newborn, and in the present study we have examined fetal, neonatal, and young (from 2 wk before birth to 16 mo postpartum) semidomesticated reindeer from northern Finland for the presence of thermogenic brown adipose tissue. Adipose tissues were removed, mitochondria were prepared, and the proteins were separated by molecular weight and blotted onto nitrocellulose membranes. The membranes were then probed for the presence of the 32,000-relative molecular weight mitochondrial uncoupling protein (UCP) unique to brown fat by use of a rabbit anti-(ground squirrel UCP) serum. Immunoreactivity at the molecular weight characteristic of UCP was present in perirenal, abdominal, inter(pre)scapular, sternal, intralumbar, vertebral, tracheal, inguinal, and omental-mesenteral adipose tissues of newborn reindeer (0-2 days of age). No immunoreactivity was detected in coronary adipose tissue. UCP was found at high levels in interscapular and perirenal adipose tissues of fetal reindeer at 2 wk before birth. Although the protein was present during the first few days postpartum, little immunoreactivity was found at 1 mo of age, and none was evident by 2 mo. UCP and its mRNA were also apparent in perirenal adipose tissue of the newborn of another species of Cervidae, the red deer. It is concluded, on the basis of the immunologic identification of UCP, that most adipose tissues of newborn reindeer represent functional brown fat but that there is a subsequent conversion to white adipose tissue by the 2nd mo of life.(ABSTRACT TRUNCATED AT 250 WORDS)


1986 ◽  
Vol 6 (7) ◽  
pp. 2382-2391
Author(s):  
C A Kaiser ◽  
D Botstein

Nine mutations in the signal sequence region of the gene specifying the secreted Saccharomyces cerevisiae enzyme invertase were constructed in vitro. The consequences of these mutations were studied after returning the mutated genes to yeast cells. Short deletions and two extensive substitution mutations allowed normal expression and secretion of invertase. Other substitution mutations and longer deletions blocked the formation of extracellular invertase. Yeast cells carrying this second class of mutant gene expressed novel active internal forms of invertase that exhibited the following properties. The new internal proteins had the mobilities in denaturing gels expected of invertase polypeptides that had retained a defective signal sequence and were otherwise unmodified. The large increase in molecular weight characteristic of glycosylation was not seen. On nondenaturing gels the mutant enzymes were found as heterodimers with a normal form of invertase that is known to be cytoplasmic, showing that the mutant forms of the enzyme are assembled in the same compartment as the cytoplasmic enzyme. All of the mutant enzymes were soluble and not associated with the membrane components after fractionation of crude cell extracts on sucrose gradients. Therefore, these signal sequence mutations result in the production of active internal invertase that has lost the ability to enter the secretory pathway. This demonstrates that the signal sequence is required for the earliest steps in membrane translocation.


1986 ◽  
Vol 6 (7) ◽  
pp. 2382-2391 ◽  
Author(s):  
C A Kaiser ◽  
D Botstein

Nine mutations in the signal sequence region of the gene specifying the secreted Saccharomyces cerevisiae enzyme invertase were constructed in vitro. The consequences of these mutations were studied after returning the mutated genes to yeast cells. Short deletions and two extensive substitution mutations allowed normal expression and secretion of invertase. Other substitution mutations and longer deletions blocked the formation of extracellular invertase. Yeast cells carrying this second class of mutant gene expressed novel active internal forms of invertase that exhibited the following properties. The new internal proteins had the mobilities in denaturing gels expected of invertase polypeptides that had retained a defective signal sequence and were otherwise unmodified. The large increase in molecular weight characteristic of glycosylation was not seen. On nondenaturing gels the mutant enzymes were found as heterodimers with a normal form of invertase that is known to be cytoplasmic, showing that the mutant forms of the enzyme are assembled in the same compartment as the cytoplasmic enzyme. All of the mutant enzymes were soluble and not associated with the membrane components after fractionation of crude cell extracts on sucrose gradients. Therefore, these signal sequence mutations result in the production of active internal invertase that has lost the ability to enter the secretory pathway. This demonstrates that the signal sequence is required for the earliest steps in membrane translocation.


1978 ◽  
Vol 33 (7) ◽  
pp. 805-808 ◽  
Author(s):  
I. Lüderwald ◽  
M. Przybylski ◽  
H. Ringsdorf ◽  
D. Silberhorn

AbstractThe combined application of field desorption and electron impact ionization techniques in the mass spectrometry of free dipeptides can be used to obtaine informations about primary structure and molecular weight. Characteristic fragmentation pathways of dipeptides are discribed and the mechanism of diketopiperazine formation is discussed.


1978 ◽  
Vol 33 (7) ◽  
pp. 809-817 ◽  
Author(s):  
I. Lüderwald ◽  
M. Przybylski ◽  
H. Ringsdorf ◽  
D. Silberhorn ◽  
H. Kaibacher ◽  
...  

AbstractThe complementary informations from field desorption and electron impact mass spectra of free tripeptides and thyrotropine releasing hormone derivatives can be used to determine primary structure and molecular weight. Characteristic and diagnostic fragmentation pathways, the formation of diketopiperazines and the temperature-dependent tendency to form amine fragments and diketopiperazines will be discussed.


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