Crystallization and characterization of human chorionic gonadotropin in chemically deglycosylated and enzymatically desialylated states

Journal Article · Tue Nov 28 00:00:00 EST 1989 · Biochemistry; (USA)

OSTI ID:6854318

Lustbader, J W; Birken, S; Pileggi, N F; Folks, M A.G.; Pollak, S; Cuff, M E; Yang, Wei; Hendrickson, W A; Canfield, R E ^[1]

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1. Columbia Univ., New York, NY (USA)

Crystals suitable for X-ray diffraction studies at moderate resolution have been grown from two forms of human chorionic gonadotropin (hCG): HF-treated hCG and neuraminidase-treated hCG. The enzymatically desialylated form of hCG produced crystals that diffract to 2.8 {angstrom} as compared to the HF-treated hCG crystals that diffract to 3.0 {angstrom}. Although it was assumed that the high and heterogeneous carbohydrate content of the glycoprotein hormones inhibited their crystallization, this report suggests that it is the negatively charged surface sugars and neither the total carbohydrate content nor its heterogeneity which interferes with crystal formation. Chemical deglycosylation resulted in significantly increased protein degradation during crystal growth. Such peptide bond cleavages were observed to a much lesser extent in the crystals grown from neuraminidase-digested hCG. Sequence analysis of the HF-treated hCG crystals suggested that up to 45% of the molecules within the crystal had an acid-labile peptide bond cleaved. In contrast, the neuraminidase-treated hCG exhibited less than 9% of this type of cleavage. The manner in which hCG was treated prior to crystallization was found to be a very important factor in the extent of peptide bound cleavages occurring during crystal growth. HF treatment of glycoproteins may render glycoproteins more susceptible to peptide bond cleavage during crystal growth.

• OSTI ID: 6854318
• Journal Information: Biochemistry; (USA), Vol. 28:24; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
GLYCOPROTEINS
AMINO ACID SEQUENCE
HCG
X-RAY DIFFRACTION
CHEMICAL BONDS
CRYSTALLOGRAPHY
ELECTROPHORESIS
NON-PEPTIDE C-N HYDROLASES
PLACENTA
PREGNANCY
WOMEN
ANIMALS
COHERENT SCATTERING
DIFFRACTION
ENZYMES
FEMALES
FETAL MEMBRANES
GONADOTROPINS
HORMONES
HYDROLASES
MAMMALS
MAN
MEMBRANES
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PITUITARY HORMONES
PRIMATES
PROTEINS
SCATTERING
VERTEBRATES
550602* - Medicine- External Radiation in Diagnostics- (1980-)