Protamine structure

Extending these ideas to enzymatic catalysis, Jiang et al. reported the use of protamine-silica hybrid microcapsules in combination with a host gel-like bead structure to encapsulate several enzymes individually in the enzymatic conversion of C02 to methanol [20]. They used a layer-by-layer (LbL) method where alternately charged layers were deposited on an enzyme-containing CaC03 core. The layers, however, were not polyelectrolytes, but protamine and silica (Scheme 5.6). 

FIGURE 4.8 Structures of representative fragments of heparin (1) and protamine (2) molecules. 

Phosphoproteins.—A chemical synthesis of partially and fully phosphorylated protamines has been described during the past year,98 and structural requirements for the enzymatic phosphorylation of phosvitin have been delineated.99 Phosphorylated forms of phosphofructokinase100 and fatty acid synthetase101 have been discovered recently both may be concerned with the regulation of their respective enzymes. 

The weakly immunogenic protamine sulfate USP (1) condenses DNA to form a toroid structure of super-coiled DNA about 50 nm in diameter (2). The DNA in this form or in the preformed LPDI complex cannot be displaced from the protamine by polycations such as spermidine and histones or by other nucleic acids like genomic DNA (2). DNA in this toroid structure is transcriptionally inactive and this conformation allows for protection of DNA from enzymatic degradation by nucleases and other environmental assaults such as mechanical stress (1,2). After the liposome surrounds the toroid, the resulting homogenous LPDI nanoparticles are slightly less than... 

I The first and simplest of them are those of sperm-head nucjeo-protein [17]. Here the nucleic acid, DNA, seems to determine the structure. In the gap already mentioned between the coils of the double spiral there is no room for any more nucleotide, but only for the smaller protamine chain, as Wilkins has shown. No similar structure has been found for natural RNA but it does occur for the combination of two different artificial poly-adenosine ribose phosphate and guanine ribose phosphate. This fact, established by Rich [18], is the best example of heterogeneous mutual coiling in vitro of polymer molecules. 

In essence the development of the anlage hypothesis arose from Kossel s use of an embryological term as applied to protamine as a basic unit of protein structure, which Block in the 1930 s translated into the constancy of thearg-lys-his ratio in the serum proteins. He changed this in his most recent suggestion that this anlage was represented by... 

A family of basic proteins associated with the chromatin in the nucleus of the cell. Protamines are characterized by a high content of arginine and replace histones in the process of spermiogenesis. See Lewis, S.D. and Ausid, J., Protamine-like proteins evidence for a novel chromatin structure, Biochem. Cell Biol. 80, 353-361,2002 Meistrich, M.L., Moha-patra, B., Shirley, C.R., and Zhao, M., Roles of transition nuclear proteins in spermiogenesis, Chromasoma 111, 483 88, 2003 Aoki,... 

V. W. and Carrell, D.T., Human protamines and the developing spermatid their structure, function, expression, and relationship with male infertility, Asian J. Androl. 5, 315-324, 2003 Erin-Lopez, J.M., Frehlich L.J., and Ausio, J., Protamines, in the footsteps of linker histone evolution, J. Biol. Chem. 281, 1, 2006. 

Certain bonds are split by proteolytic enzymes, not merely because they belong to a given protein, but because their structure, location, and/or availability fulfill certain requirements. Thus, the nomenclature of proteolytic enzymes should not be based upon the name of the proteins of which these enzymes have been tested for the first time, but upon factors directly connected with the bonds. A good illustration of this important principle is given by the following case It was claimed that pancreas contains a protaminase because autolyzates of the gland displayed considerable activity against protamines (138, 139). It turned out later that pancreas actually contains a second carboxypeptidase which easily splits the basic bonds of these peculiar proteins. 

Insulin is able to form at least six different crystalline modifications, either zinc-free or with two or four zinc ions per hexamer. The addition of protamine and phenol also affects the structure of the crystal (for a review see Brange, 1987). 

Shortly after pronucleus formation and entry into S phase, transcription initiates in both pronuclei of the one-cell embryo (Figure 6). The male pronucleus supports higher levels of transcription than the female pronucleus, and this difference is attributed to their differences in chromatin structure that reflects their different histories (e.g., the protamine-histone exchange that occurs in the male pronucleus affords an opportunity for the sequestration of maternal transcription factors that is not available to the female pronucleus whose DNA is already packaged into chromatin). The first... 

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