Dimerization of Human Growth Hormone by Zinc

Cunningham, Brian C.; Mulkerrin, Michael G.; Wells, James A.

doi:10.1126/science.1907025

Cited by 217 publications

(133 citation statements)

References 21 publications

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“…However, Zn(II) (added as ZnCl 2 ) was unable to inhibit the oxidation of hGH until the ratio of [Zn(II)]:[Cu(II)] was higher than 80:1. This result suggests a strong binding of Cu(II) to the metalbinding site of hGH and is particularly interesting with regard to the fact that Zn(II) regulates storage and biological activity of hGH under physiological conditions (20,40).…”

Section: The Importance Of An Intact Metal-binding Site and Site Specmentioning

confidence: 99%

“…The potential oxidation sites on these fragments are Met 170 and/or Glu 174 . The Glu 174 residue is the third component of the metal-binding site in addition to the two His residues (20). Met 170 , although buried in the hydrophobic core, is also located close to the metal-binding site according to the crystal structure of hGH (24).…”

Section: Figmentioning

confidence: 99%

“…This is consistent with the observed loss of T3 and T4. Notably His 18 and His 21 are components of the metal-binding site of hGH (20). A third His residue, His 151 , is located next to the known deamidation site of the protein and solvent accessible (21).…”

Section: Figmentioning

confidence: 99%

“…Ascorbate/ Cu(II)/O 2 has not only been used extensively as a non-enzymatic model oxidizing system but is of physiological relevance to conditions of oxidative stress. hGH was chosen because of its well characterized metal-binding site which shows high affinity for divalent metal ions, such as Zn(II) and Co(II) (20). This site consists of His 18 and His 21 from helix I, and Glu 174 from helix IV.…”

mentioning

confidence: 99%

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Metal-catalyzed Oxidation of Histidine in Human Growth Hormone

Zhao

Ghezzo-Schöneich

Aced

et al. 1997

Journal of Biological Chemistry

109

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In physiological compartments, provided with suitable reducing agents, transition metals are able to catalyze the activation of O 2 to various reactive oxygen species (ROS) 1 which readily attack biomolecules. The metal-catalyzed oxidation (MCO) of proteins plays an important role during oxidative stress and aging where modified proteins may accumulate in tissue (1-9). In addition, MCO also presents a stability problem for the biotechnological manufacturing of proteins (10, 11).A unique feature often observed during MCO of proteins is that only a few amino acid residues within a certain domain of the given protein are modified (2, 12). Such site specificity is attributed to the generation of ROS at specific metal-binding sites, where the highly reactive ROS attack labile functional groups nearby rather than diffuse into the bulk medium. It has been shown that most of the enzymes labile to MCO require metals for activity (13). The oxidation of these enzymes is less sensitive to the inhibition by exogenous ROS scavengers than would be expected on the basis of known rate constants for the reactions of specific ROS with these scavengers. However, one problem associated with all these studies is that neither the oxidizing species nor the intermediary protein-transition metal complexes formed during MCO of proteins have been well characterized. This is most pertinent to copper-catalyzed oxidation (i.e. to the frequently used ascorbate/Cu(II)/O 2 system) involving the Cu(II)/Cu(I) redox couple (2). Here, Cu(II) will most probably require a different geometry and different ligands within the protein ligand sphere than Cu(I). An initial reduction of Cu(II), bound to a metal-binding site, to Cu(I) may change the geometry of the protein-metal complex, and possibly even release Cu(I) from the metal-binding site. On the other hand, the metal may be retained when (i) the protein is flexible enough to adapt to the new geometrical requirements of the reduced metal, or (ii) re-oxidation of the metal by molecular oxygen or reduction products of molecular oxygen such as superoxide or hydrogen peroxide occurs faster than the release of the reduced metal from the metal-binding site.In a recent example for electron transfer coupled ligand dynamics in the model complex Cu(I/II)(TTCN) 2 , we could show that oxidation of tetrahedral [Cu(I)(TTCN) 2 ] ϩ potentially led to the loss of a ligand to yield [Cu(II)(TTCN)(H 2 O) 3 ] 2ϩ before geometrical reorganization around the Cu(II) atom allowed the addition of TTCN to give the final product, octahedral [Cu(II)(TTCN) 2 ] 2ϩ . 2 Analogous mechanisms may lead to kinetic complexities during protein oxidation which may be reflected in oxidation yields and kinetics as well as the nature of the oxidation products.One amino acid particularly affected by MCO is histidine (His) (15-17). There is as yet no detailed mechanism available for His oxidation in proteins, except a crystallographic study which showed the feasibility of metal-catalyzed processes within the metal-binding domain of glutamine syn...

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Section: The Importance Of An Intact Metal-binding Site and Site Specmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Metal-catalyzed Oxidation of Histidine in Human Growth Hormone

Zhao

Ghezzo-Schöneich

Aced

et al. 1997

Journal of Biological Chemistry

109

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“…The lack of this dimeric form in the hGH-hEpo samples would suggest that the C-terminal of hGH might be involved in this process. Indeed Glu (174) in the C-terminal α-helix has been identified as an important residue for hGH dimerization [28]. In additional experiments these products were shown to be glycosylated as they migrated at a lower molecular mass when treated with 2,N-glycosidase to remove N-linked oligosaccharides (data not shown).…”

Section: Resultsmentioning

confidence: 89%

Sorting of growth hormone–erythropoietin fusion proteins in rat salivary glands

Samuni

Zheng

Cawley

et al. 2008

Biochemical and Biophysical Research Communications

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Neuroendocrine and exocrine cells secrete proteins in either a constitutive manner or via the regulated secretory pathway (RSP), but the specific sorting mechanisms involved are not fully understood. After gene transfer to rat salivary glands, the transgenic model proteins human growth hormone (hGH) and erythropoietin (hEpo) are secreted primarily into saliva (RSP; exocrine) and serum (constitutive; endocrine), respectively. We hypothesized that fusion of hGH at either the C-terminus or the N-terminus of hEpo would re-direct hEpo from the bloodstream into saliva. We constructed and expressed two fusion proteins, hEpo-hGH and hGH-hEpo, using serotype 5-adenoviral vectors, and delivered them to rat submandibular glands in vivo via retroductal cannulation. Both the hEpohGH and hGH-hEpo fusion proteins, but not hEpo alone, were secreted primarily into saliva (p<0.0001 and P=0.0083, respectively). These in vivo studies demonstrate for the first time that hGH, in an N-as well as C-terminal position, influences the secretion of a constitutive pathway protein.

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Hormones, Human Growth Hormone

Becker¹,

MacKellar²,

Riggin³

et al. 2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Human growth hormone (hGH), a protein hormone produced and secreted by the somatotropic cells of the anterior pituitary, plays a key role in somatic growth through its effects on the metabolism of proteins, carbohydrates, and lipids. The biological properties of hGH are diverse and complex, with the molecule exhibiting anabolic activity, insulin‐like and diabetogenic activities, and lactogenic activity, as well as producing effects on water and salt retention. First isolated from the pituitary gland, hGH is produced using recombinant DNA technology and has been approved for use as a human pharmaceutical in the treatment of growth failure owing to hGH deficiency and in the treatment of Turner's syndrome in Europe and Japan. In addition, hGH is being investigated for use in treating burns, various wounds, osteoporosis, cachexia, and other conditions. Human growth hormone is one of the largest selling therapeutic proteins produced by recombinant DNA technology.

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Dimerization of Human Growth Hormone by Zinc

Cited by 217 publications

References 21 publications

Metal-catalyzed Oxidation of Histidine in Human Growth Hormone

Metal-catalyzed Oxidation of Histidine in Human Growth Hormone

Sorting of growth hormone–erythropoietin fusion proteins in rat salivary glands

Hormones, Human Growth Hormone

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