Protem

Interactions between macromolecules (protems, lipids, DNA,.. . ) or biological structures (e.g. membranes) are considerably more complex than the interactions described m the two preceding paragraphs. The sum of all biological mteractions at the molecular level is the basis of the complex mechanisms of life. In addition to computer simulations, direct force measurements [98], especially the surface forces apparatus, represent an invaluable tool to help understand the molecular interactions in biological systems. 

Protems can be physisorbed or covalently attached to mica. Another method is to innnobilise and orient them by specific binding to receptor-fiinctionalized planar lipid bilayers supported on the mica sheets [15]. These surfaces are then brought into contact in an aqueous electrolyte solution, while the pH and the ionic strength are varied. Corresponding variations in the force-versus-distance curve allow conclusions about protein confomiation and interaction to be drawn [99]. The local electrostatic potential of protein-covered surfaces can hence be detemiined with an accuracy of 5 mV. 

Recent developments m calorimetry have focused primarily on the calorimetry of biochemical systems, with the study of complex systems such as micelles, protems and lipids using microcalorimeters. Over the last 20 years microcalorimeters of various types including flow, titration, dilution, perfiision calorimeters and calorimeters used for the study of the dissolution of gases, liquids and solids have been developed. A more recent development is pressure-controlled scamiing calorimetry [26] where the thennal effects resulting from varying the pressure on a system either step-wise or continuously is studied. 

Nucleosome (Section 28 9) A DNA-protem complex by which DNA IS stored in cells... 

Total sohds Total. a protem Cocoa protein Fat Ash Total carbohydrates... 

R Sanchez, A Sail. Advances in comparative protem-stiaicture modeling. Cuit Opm Stiaict Biol 7 206-214, 1997. 

The leucme-reversible toxicity of 5,5, -trifluoroleudne (10) to microorganisms, such as Escherichia coli, has been attributed to incorporation of JO into protem [32] and to the action of 10 as a false feedback inhibitor of a-isopropylmalate... 

Isomenyl (Kaken) Medihaler-Iso (Dainippon) Protemal (Nikken) Protemol (Nikken)... 

Estimation of molecular weights of protems by gel filtration. Nature 796, 36-39 (1962). 

Cecil, R., and R. G. Wake The reaction of inter- and intra-chain disulphide bonds in protems with sulfite. Biochemic. Journ. 82, 401—406 (1962). 

Polarization Properties. One of Ae key attractions of XAS for biological systems is Ae ability to study unoriented samples such as protems in solution. If samples can be oriented, however, it is possible to greatly enhance Ae information content of XAS spectra. In particular, it is possible to obtain direct information about Ae relative orientation of specific structural features. These experiments are possible because the synchrotron X-ray beam is highly plane polarized. Several examples of polarized XAS of biologicA samples are Ascussed below. 

The present results Aus demonstrate Aat while Ae inAvidual mean motions of boA Ae Cu and Ae S(Met) atoms are normal, Aeir relative motion must be largely uncorrelated in cider to account for Ae non-observation of Cu-S(Met) EXAFS. The combination of crystallographic and EXAFS mformation is Aus able to shed light on Ae dynamic motion of Ae protem. 

LaRochelle, W J. andFroehner, S. C. (1986) Determination of the tissue distributions and relative concentrations of the postsynaptic 43-kDa protem and the acetylcholine receptor in Torpedo J Biol Chem 261, 5270—5274... 

Concentrate the avidm-protem conjugate mixture to 1-2 mL in a Centncon-30 (Amicon, Beverly, MA) or equivalent centrifuge tube concentrator. 

Faraday (1857) 9 First mention of gold-protem complexing and interaction with light... 

Review methods for protem assay including absorbance and colorimetric (Lowry, Biuret, Bradford, BCA)... 

Lflbke, K, Schrdder, E Kloss, G 1975, Chemie und Biochenue der Ammosauren Peptide und Proteme, Vol I, Thieme Stuttgart... 

Figure 371 Antigens may be detected in cells or tissue sections through the use of protein A-coated gold particles. The binding of a specific antibody to its target antigen can be localized by the immunoglobulin binding capability of protem A, which occurs in the Fc region of the antibody.

Johns Hopkins University OWL Web http //www.gdb.org.Dan/protems/owl.html... 

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