Insulin Crystals. VII. The Growth of Insulin Crystals.

Schlichtkrull, J.; Ekholm, Reino; Norman, Arne; Noer, B.; Reio, L.

doi:10.3891/acta.chem.scand.11-1248

Cited by 32 publications

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“…There is a total amount of 11.6 zinc ions in the hexamer; this corresponds to about 2.3%. This figure is sensibly near 2.5%, which is the value reported by 177 Schlichtkrull for the zinc content in rhombohedral insulin crystal preparations in acetate buffer at neutral pH [18].…”

Section: The Bound Zinc Positionssupporting

confidence: 58%

“…Some variation in the insulin storage crystal in the presence of the other numerous molecular species, such as calcium ions, arginine, lysine and the connecting peptide present in the storage granule, is perhaps to be expected. Supporting this is the observation that in the laboratory with pig and beef insulin we find the crystal form and the conditions of precipitation can easily be changed by adding various molecules to the solution (Cutfield, Dodson, Tolley, unpublished, [18]). …”

Section: Crystallization Within the Storage Vesiclementioning

confidence: 75%

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Role of zinc in insulin biosynthesis

et al. 1980

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Summary. The behaviour of proinsulin and insulin in the presence of zinc suggests it plays an important role in insulin's production in the B-cell for the vast majority of animal species. The postulate that proinsulin forms a zinc containing hexamer soon after its synthesis and that this organization of the molecule is maintained through all the subsequent processes is supported by our observation that the proinsulin hexamer is converted readily into the insulin hexamer. In addition the zinc ions enhance proinsulin's solubility and render insulin insoluble. Zinc ions also appear to play an important role in the microcrystalline character of the precipitated insulin granule. There may be advantages in condensing the stored material in this way; it will reduce contact with the surrounding membrane where the converting, and possibly other enzymes, are thought to be located, and it will tend to exclude incompletely converted hexamers.

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Section: The Bound Zinc Positionssupporting

confidence: 58%

Section: Crystallization Within the Storage Vesiclementioning

confidence: 75%

Role of zinc in insulin biosynthesis

et al. 1980

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“…Sometimes material to be employed in one crystallization (of the order of 200/Ag to be dissolved in about [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Al) was weighed out separately in the capillary tube. Stock solutions prepared with 1 mg of proinsulin in 25-100 Mil were also employed.…”

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confidence: 99%

“…(2) In citrate buffer at pH 7.25: Proinsulin (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) performed by the initial addition of the ammonium sulfate solution at room temperature followed by removal of the preparation to the cold room.…”

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Proinsulin: Crystallization and Preliminary X-Ray Diffraction Studies

Fullerton

Potter

Low

1970

Proc. Natl. Acad. Sci. U.S.A.

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Abstract. Bovine proinsulin has been crystallized under a variety of conditions at both neutral and acid pH. Microtechniques were employed with sample weights of about 200 jig and volumes of 5-20 1AL The crystalline preparations all differ from each other morphologically.X-ray photographs of one form, tetragonal bipyramids grown at pH 3 with added ammonium sulphate solution, established the space group P41212 (or its enlantiomorph P43212). The cell dimensions are a = 50.8 i 0.2 A, c = 148.0 + 0.4 A. The asymmetric unit in this form is a dimer of proinsulin which is also the dominant species in solution at this pH.Introduction. Following the studies of Steiner arid his co-w%-orkersl2 who established that insulin is synthesized via a single chain precursor protein, proinsulin has been isolated and characterized from bovine,3-6 porcine,' cod,8 anglerfish,9 and human10"1 tissues. The connecting peptide segment of proinsulin which links the carboxyl-terminal group of the insulin B chain to the amino-terminal group of the insulin A chain is cleaved in vivo by proteolysis. The lengths and sequences of the C-peptide vary markedly between species. In bovine proinsulin, where the connecting peptide is 30 amino acid residues long," the proinsulin molecule with a single 81 residue chain has a molecular weight of 868.5.

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Nucleation and crystal proliferation kinetics: Amorphous‐crystalline transformation of basic copper carbonates

Hsu

1971

AIChE Journal

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The transformation of amorphous basic copper carbonate precipitates into the crystalline form in aqueous solutions was experimentally studied. The unique blue-to-green color change and drastic volume reduction of the precipitates in transition made continuous observation and quantitative determination of the transformation process feasible. The transformation, which involves both nucleation and crystal growth proliferation, was autocatalytic. Experimental results are in good agreement with the rate equation formulated on the two-stage kinetics model postulated for the system. Also studied were the effects of temperature and precipitate concentration on the rate of transformation. In the temperature range between 34" and 39"C., the apparent nucleation activation energy was 19.8 kcal./g.-mole.The art and science of crystallization are of interest to a wide range of physical and biological scientists and technologists (1, 6, 11, 16, 20, 30). The vast diversity of interest and objectives calls for the study of mechanism and techniques, such as to grow large perfect crystals, to grow crystals of uniform sizes, and to prevent the formation of crystals. The fundamental forces involved in all types of crystallization, whether in polymers, in organic and inorganic salts, or in metals, are believed to be essentially identical, but various crystallizing systems may show totally different behavior in the course of crystallization under different physical situations.A great amount of work has been done on the various aspects of crystallization with crystallizing systems as diverse as insulin and synthetic zeolites. The effects of physical factors, such as degree of supersaturation, temperature, and cooling rate, on the growth rate of crystals (7, 13, 18, 25), size distribution (4, 15, 17, 29), and crystal morphology (2, 26) have been extensively investigated.It is well established that there are two processes, nucleation and crystal growth, which are instrumental in the crystallization process. Because the elementary kinetic steps are little known and are specific for different systems, only empirical kinetic treatment of individual systems has been advanced by various workers ( 1 0,17,21,23,24,27).The system reported here is a complex inorganic precipitate, basic copper carbonate, formed in an aqueous medium. The stoichiometric relation of the reaction under controlled conditions conforms to the following equations 2NazC03 + 2CuS04 + H 2 0 = CUCO~.CU(OH)Z ( 9 , l Q ) :The initial precipitates formed by mixing aqueous sodium carbonate and cupric sulfate solutions were gelatinous and noncrystalline, but were able to transform themselves into crystalline particles of pure malachite on aging ( 9 , 2 8 ) .The purpose of the present work is to study the kinetics AlChE Journal (Vol. 17, NO. 6) of nucleation and crystal growth inherent in such transformation. Incidentally, this crystallizing system is particularly desirable in that the transformation process can be visually tracked. THEORYCrystal growth can be considered to consist ...

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Insulin Crystals. VII. The Growth of Insulin Crystals.

Cited by 32 publications

References 0 publications

Role of zinc in insulin biosynthesis

Role of zinc in insulin biosynthesis

Proinsulin: Crystallization and Preliminary X-Ray Diffraction Studies

Nucleation and crystal proliferation kinetics: Amorphous‐crystalline transformation of basic copper carbonates

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