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941.
Protein–DNA interactions are involved in many biochemical pathways and determine the fate of the corresponding cell. Qualitative and quantitative investigations on these recognition and binding processes are of key importance for an improved understanding of biochemical processes and also for systems biology. This review article focusses on atomic force microscopy (AFM)-based single-molecule force spectroscopy and its application to the quantification of forces and binding mechanisms that lead to the formation of protein–DNA complexes. AFM and dynamic force spectroscopy are exciting tools that allow for quantitative analysis of biomolecular interactions. Besides an overview on the method and the most important immobilization approaches, the physical basics of the data evaluation is described. Recent applications of AFM-based force spectroscopy to investigate DNA intercalation, complexes involving DNA aptamers and peptide– and protein–DNA interactions are given. 相似文献
942.
Sophie Greistorfer Johannes Suppan Norbert Cyran Waltraud Klepal Robert Farkas Livia Rudoll Janek von Byern 《Journal of morphology》2020,281(9):1059-1071
The most common European gastropod species, Arion vulgaris, is one of the most troublesome pests for private garden owners and commercial agriculturists. The sticky and hard to remove secretion produced by these animals allows them to overcome most artificial and natural barriers. However, this highly adherent biopolymer has recently shown great potential for novel wound-healing applications in medicine. Nevertheless, our knowledge of the underlying gland system is still limited and few studies on the ventral gland system are available. We studied the lateral and ventral pedal glands in Arion vulgaris to determine their secretory content histochemically and through lectin assays. Using these histological and histochemical methods we differentiate five gland types with different mucus composition in the lateral pedal region of the foot of Arion vulgaris. These contain sulphated and carboxylated mucosubstances (positive Alcian blue staining) but lack hexose-containing mucosubstances (negative PAS staining). In the ventral pedal region, four gland types can be differentiated producing sulphated and carboxylated mucosubstances. Within the ventral mucus, a high affinity for the lectins PNA and WGA is observed. While the lateral glands are histochemically negative for PAS, a positive staining with the lectin JAC is observed. Arion vulgaris shows clear morphological differences from other arionid species. This raises the question whether the variation in the chemistry of the secretory material and mucus composition is the result of different functions and/or is related to the animals' different environmental conditions. A comparison of some glands of Arion vulgaris with those of the helicid species Helix pomatia and Cepaea hortensis indicates morphological similarities. 相似文献
943.
Rickelt S Kuhn C Winter-Simanowski S Zimbelmann R Frey N Franke WW 《Cell and tissue research》2011,346(3):347-359
The protein myozap, a polypeptide of 54 kDa, has recently been identified as a component of the cytoplasmic plaques of the
composite junctions (areae compositae) in the myocardiac intercalated disks and of the adherens junctions (AJs) in vascular endothelia. Now we report that using
very sensitive new antibodies and drastic localization methods, we have also identified this protein as a component of the
AJ plaques in simple and complex epithelia, in the adluminal cell layer of the transitional epithelium of the urinary tract
and in certain cell layers of diverse stratified epithelia, including gingiva, tongue, pharynx and esophagus, cervix, vagina
and epidermis. Myozap has not been identified in desmosomal and tight junction plaques. We have also detected protein myozap
in AJ structures of carcinomas. The discovery of a novel major protein in AJ plaques now calls for re-examinations of molecular
interactions in AJ formation and maintenance and also offers a new marker for diagnostic immunocytochemistry. We also discuss
the need for progressive unravelling, extractive treatments and buffer rinses of sections and cultured cells to reveal obscured
or masked antigens, before definitive negative conclusions in immunohistochemistry can be made. 相似文献
944.
Gericke A Sniatecki JJ Mayer VG Goloborodko E Patzak A Wess J Pfeiffer N 《American journal of physiology. Heart and circulatory physiology》2011,300(5):H1602-H1608
Acetylcholine regulates perfusion of numerous organs via changes in local blood flow involving muscarinic receptor-induced release of vasorelaxing agents from the endothelium. The purpose of the present study was to determine the role of M?, M?, and M? muscarinic acetylcholine receptors in vasodilation of small arteries using gene-targeted mice deficient in either of the three receptor subtypes (M1R(-/-), M3R(-/-), or M5R(-/-) mice, respectively). Muscarinic receptor gene expression was determined in murine cutaneous, skeletal muscle, and renal interlobar arteries using real-time PCR. Moreover, respective arteries from M1R(-/-), M3R(-/-), M5R(-/-), and wild-type mice were isolated, cannulated with micropipettes, and pressurized. Luminal diameter was measured using video microscopy. mRNA for all five muscarinic receptor subtypes was detected in all three vascular preparations from wild-type mice. However, M(3) receptor mRNA was found to be most abundant. Acetylcholine produced dose-dependent dilation in all three vascular preparations from M1R(-/-), M5R(-/-), and wild-type mice. In contrast, cholinergic dilation was virtually abolished in arteries from M3R(-/-) mice. Deletion of either M?, M?, or M? receptor genes did not affect responses to nonmuscarinic vasodilators, such as substance P and nitroprusside. These findings provide the first direct evidence that M? receptors mediate cholinergic vasodilation in cutaneous, skeletal muscle, and renal interlobar arteries. In contrast, neither M? nor M? receptors appear to be involved in cholinergic responses of the three vascular preparations tested. 相似文献
945.
Stefan Bayer Ludger Keilig Dominik Kraus Manfred Grüner Helmut Stark Sebastian Mues Norbert Enkling 《Gerodontology》2011,28(3):221-226
Gerodontology 2010; doi: 10.1111/j.1741‐2358.2009.00352.x Influence of the lubricant and the alloy on the wear behaviour of attachments Objectives: Wear of attachments leads to a loss of retention and reduces the function of overdentures. This study evaluated the retention force changes of an attachment system for overdentures. The influence of the lubricant and the alloy on wear constancy was examined. Methods: Cylindrical anchors of the Dalbo®‐Z system were tested (Cendres+Métaux SA). Three groups of alloy‐lubricant combinations were generated 1.Elitor®/NaCl‐solution (EN) 2.Elitor®/Glandosane®aquadest. (EG) and 3.Valor®/Glandosane®/aquadest. (VG). Ten samples of each group were subjected to 10 000 insertion–separation cycles. Results: For the EN‐group, this led to a large increase in retention force. The EG‐ and VG‐group showed a constant decrease after an initial increase in retention force at the beginning of the wear simulation. The change of the alloy caused no statistically significant differences. The use of a more viscous lubricant reduced the retention force increase significantly. Conclusions: The use of a lubricant which simulates clinical conditions is an absolute need for wear simulation because the retention force changes are influenced enormously. The change of the alloy at the Dalbo®‐Z system did not influence the wear behaviour. As a slight decrease in retention force was recorded, it is useful for an attachment system to allow compensation with an adjustable matrix. 相似文献
946.
947.
A short synthesis of alkyl 2-(bromomethyl)aziridine-2-carboxylates and alkyl 3-bromoazetidine-3-carboxylates was developed
involving amination, bromination, and base-induced cyclization of alkyl 2-(bromomethyl)acrylates. The aziridines are the kinetically
favored cyclization products and could be transformed into 3-bromoazetidine-3-carboxylic acid derivatives via thermal isomerization.
The new small-membered azaheterocyclic α- and β-amino acid derivatives contain a bromo-substituted carbon center as a useful
moiety for functionalization. Transformation of these functionalized azaheterocycles via nucleophilic substitution with carbon,
sulfur, oxygen, and nitrogen nucleophiles and via elaboration of the amino and carboxyl group provided a broad range of new
conformationally constrained aziridine-2- and azetidine-3-carboxylic acid derivatives, which are of interest from a biological
point-of-view as well as for applications in the field of foldamers. 相似文献
948.
Nagel L Plattner C Budke C Majer Z DeVries AL Berkemeier T Koop T Sewald N 《Amino acids》2011,41(3):719-732
In Arctic and Antarctic marine regions, where the temperature declines below the colligative freezing point of physiological
fluids, efficient biological antifreeze agents are crucial for the survival of polar fish. One group of such agents is classified
as antifreeze glycoproteins (AFGP) that usually consist of a varying number (n = 4–55) of [AAT]
n
-repeating units. The threonine side chain of each unit is glycosidically linked to β-d-galactosyl-(1 → 3)-α-N-acetyl-d-galactosamine. These biopolymers can be considered as biological antifreeze foldamers. A preparative route for stepwise synthesis
of AFGP allows for efficient synthesis. The diglycosylated threonine building block was introduced into the peptide using
microwave-enhanced solid phase synthesis. By this versatile solid phase approach, glycosylated peptides of varying sequences
and lengths could be obtained. Conformational studies of the synthetic AFGP analogs were performed by circular dichroism experiments
(CD). Furthermore, the foldamers were analysed microphysically according to their inhibiting effect on ice recrystallization
and influence on the crystal habit. 相似文献
949.
950.