Annals of the New York Academy of Sciences 

About: Annals of the New York Academy of Sciences is an academic journal published by Wiley-Blackwell. The journal publishes majorly in the area(s): Receptor & Population. It has an ISSN identifier of 0077-8923. Over the lifetime, 61286 publications have been published receiving 1980808 citations. The journal is also known as: New York Academy of Sciences. Annals & Ann. N.Y. Acad. Sci..

The Attractions of Proteins for Small Molecules and Ions

Abstract: The number and variety of known compounrjs between proteins and small molecules are increasing rapidly and make a fascinating story. For instance, there are the compounds of iron, which is carried in our blood plasma by a globulin, two atoms of iron to each molecule of globulin held in a rather tight salt-lie binding? which is stored as ferric hydroxide by ferritin much as water is held by a sponge? and which functions in hemoglobin, four iron atoms in tight porphyrin complexes in each protein molecule. Or, there are many compounds of serum albumin, which was used during the war by many chemists, most of whom found at least one 6ew compound. This molecule, which has about a hundred carboxyl radicals, each of which can take on a proton, and about the same number of ammonium radicals, each of which can dissociate a proton, has one single radical which combines with mercuric ion so firmly that two albumin molecules will share one mercury atom if there are not enough to go a r ~ u n d . ~ At the present stage of rapid growth of known compounds, it seems more profitable for me to make no attempt to catalogue the various classes of compounds, but to discuss the general principles involved, in the hope that this will make more useful the information which is accumulating so rapidy from so many laboratories. We want to know of each molecule or ion whicb can combine with a protein molecule, /‘How many? How tightly? Where? Why?” The answer to the first two questions, and sometimes to the third, can be furnished by the physical chemist, but he will often need to team with an organic chemist to determine the effect of altering specified groups to find if they are reactive. The determination of function iç a complicated problem which may be the business of the physiologist or physiological chemist. But the answers to both of the more complicated problems will depend on the answers to the simpler questions, “HOW many?” and “How tightly bound?” If the various groups on a protein molecule act independently, we can apply the law of mass action as though each group were on a separate molecule,4 and the strength of binding can be expressed as the constant for each group. Often, a single constant will express the behavior of severa1 groups. If the constants are widely spread, as those for the reaction of hydrogen ion with carboxylate ions, with imidazoles and with amines, the interpretation is simple. If the separation is less, it is very difficult to distinguish the case of different intrinsic affinities from the case of interaction among the groups. We know that such interaction occurs in simple moleculeç in which a reac-

Disc electrophoresis – ii method and application to human serum proteins*

Abstract: Summary The technique of disc electrophoresis has been presented, including a discussion of the technical variables with special reference to the separation of protein fractions of normal human serum.

The Brain's Default Network Anatomy, Function, and Relevance to Disease

Abstract: Thirty years of brain imaging research has converged to define the brain’s default network—a novel and only recently appreciated brain system that participates in internal modes of cognition Here we synthesize past observations to provide strong evidence that the default network is a specific, anatomically defined brain system preferentially active when individuals are not focused on the external environment Analysis of connectional anatomy in the monkey supports the presence of an interconnected brain system Providing insight into function, the default network is active when individuals are engaged in internally focused tasks including autobiographical memory retrieval, envisioning the future, and conceiving the perspectives of others Probing the functional anatomy of the network in detail reveals that it is best understood as multiple interacting subsystems The medial temporal lobe subsystem provides information from prior experiences in the form of memories and associations that are the building blocks of mental simulation The medial prefrontal subsystem facilitates the flexible use of this information during the construction of self-relevant mental simulations These two subsystems converge on important nodes of integration including the posterior cingulate cortex The implications of these functional and anatomical observations are discussed in relation to possible adaptive roles of the default network for using past experiences to plan for the future, navigate social interactions, and maximize the utility of moments when we are not otherwise engaged by the external world We conclude by discussing the relevance of the default network for understanding mental disorders including autism, schizophrenia, and Alzheimer’s disease

The effects of shape on the interaction of colloidal particles

Abstract: Introdzution. The shapes of colloidal particles are often reasonably compact, so that no diameter greatly exceeds the cube root of the volume of the particle. On the other hand, we know many coiloids whose particles are greatly extended into sheets (bentonite), rods (tobacco virus), or flexible chains (myosin, various Iinear polymers). In some instances, a t least, solutions of such highly anisometric particles are known to exhibit remarkably great deviations from Raoult’s law, even to the extent that an anisotropic phase may separate from a solution in which the particles themselves occupy but one or two per cent of the total volume (tobacco virus, bentonite). We shall show in what follows how such results may arise from electrostatic repulsion between highly anisometric particles. Most colloids in aqueous solution owe their stability more or less to electric charges, so that each particle will repel others before they come into actual contact, and effectively claim for itself a greater volume than what it actuaily occupies. Thus, we can understand that colloids in general are apt to exhibit considerable deviations from Raoult’s law and that crystalline phases retaining a fair proportion of solvent may separate from concentrated solutions. However, if we tentatively increase the known size of the particles by the known range of the electric forces and multiply the resulting volume by four in order to compute the effective van der Waal’s co-volume, we have not nearly enough to explain why a solution of 2 per cent tobacco virus in 0.005 normal NaCZ forms two phases.

Disc electrophoresis-i background and theory*

Abstract: Although electrophoresis is one of the most effective methods for the separation of ionic components of a mixture, the resolving power of different electrophoretic methods is quite variable. To separate two component ions, it is necessary to permit migration to continue until one of the kinds of ions has traveled at least one thickness of the volumes that it initially occupied (the starting zone) further than the other. However, the sharpness, and therefore the resolution, of the zones occupied by each ion diminishes with time because of the spreading of the zones as a result of diffusion. Remarkable resolution has been achieved when advantage is taken of the frictional properties of gels to aid separation by seiving at the molecular level (see Smithies’). A new method, disc electrophoresis, t has been designed that takes advantage of the adjustability of the pore size of a synthetic gel and that automatically produces starting zones of the order of 10 microns thickness from initial volumes with thicknesses of the order of centimeters. High resolution is thus achieved in very brief runs. With this technique, over 20 serum proteins are routinely separated from a sample of whole human serum as small as one microliter in a 20-minute run (see FIGURE 1) . Direct analysis of even very dilute samples becomes routine because the various ions are automatically concentrated to fixed high values at the beginning of the run just prior to separation. Preliminary laboratory studies and theoretic considerations provide evidence of the applicability of this technique to a wide range of ionic species for both analytic and large-scale preparative purposes. Theory has also provided the basis for a simple application of disc electrophoresis to the simultaneous determination of both the free mobility and the aqueous diffusion constant of a protein. This report will detail some mechanisms that provide a rationale for the resolution afforded by zone electrophoresis in many gels; will develop the theory of some new modifications of zone electrophoresis that have been designed to take maximum advantage of these mechanisms; and will provide some examples of the results that disc electrophoresis has produced.