Protein as function

An effective method for localizing causes of redox potentials is to plot the total backbone and side chain contributions to ( ) per residue for homologous proteins as functions of the residue number using a consensus sequence, with insertions treated by summing the contribution of the entire insertion as one residue. The results for homologous proteins should be examined for differences in the contributions to ( ) per residue that correlate with observed redox potential differences. These differences can then be correlated with any other sequence-redox potential data for proteins that lack crystal or NMR structures. In addition, any sequences of homologous proteins that lack both redox potentials and structures should be examined, because residues important in defining the redox potential are likely to have semi-sequence conservation of a few key amino acid types. 

Fig. 11.5. Z-scores of native proteins as function of sequence length.

PROTEINS AS FUNCTIONAL COMPONENTS IN FOODS 7.4.1 Muscle Proteins... 

Vrlens J, Owsianik G, Voets T, Droogmans G, Nilius B (2004) Invertebrate TRP proteins as functional models for mammalian channels. Pfiugers Arch 449 213... 

Fig. 2 Charge of weak and strong polyelectrolytes, and of proteins as function of the pH [1]...

Noble M E M, R K Wierenga, A-M Lambeir, F R Opperdoes, W H Thunnissen, K H Kalk, H Groendijk and W G J Hoi 1991. The Adaptability of the Active Site of Trypanosomal Triosephosphate Isomerase as Observed in the Crystal Structures of Three Different Complexes. Proteins Structure, Function and Genetics 10 50-69. 

Fig. 29. Rejection of test proteins as a function of molecular weight, in a series of ultrafiltration membranes with different weight cut-offs (69).

Protein S. Protein S is a single-chain molecule of approximately 78,000 daltons that contains 10 y-carboxy glutamic acid residues in the NH -terminal portion of the molecule. Protein S is a regulatory vitamin K-dependent protein. In plasma 40% of this protein circulates free and 60% circulates bound to C4b binding protein. Free Protein S functions as a nonenzymatic cofactor that promotes the binding of Protein C to membrane surfaces (22—25). 

The thermodynamic stability of a protein in its native state is small and depends on the differences in entropy and enthalpy between the native state and the unfolded state. From the biological point of view it is important that this free energy difference is small because cells must be able to degrade proteins as well as synthesize them, and the functions of many proteins require structural flexibility. 

In this chapter we describe some examples of structures of membrane-bound proteins known to high resolution, and outline how the elucidation of these structures has contributed to understanding the specific function of these proteins, as well as some general principles for the construction of membrane-bound proteins. In Chapter 13 we describe some examples of the domain organization of receptor families and their associated proteins involved in signal transduction through the membrane. 

FIGURE 5.16 The solubility of most globular proteins is markedly influenced by pH and ionic strength. This figure shows the solubility of a typical protein as a function of pH and various salt concentrations. 

Complexes of O2 with [ TMPA)CuVRCN)] [TMPA = tris(2-pyridylmethyl)-amine] as functional models for proteins 98PAC855. 

---