title: Hexa-thiocarbamoyl phenyl PEG5K Hb: vasoactivity and structure: influence of rigidity of the conjugation linkage on the PEGylation induced plasma expander-like solution properties of PEG-Hb adducts.
abstract: A new hexaPEGylated hemoglobin, (TCP-PEG5K)(6)-Hb (TCP, thiocarbamoyl phenyl) has been developed using PEG-phenyl-isothiocyanate and its vasoactivity and structure has been investigated. Of the six PEG5K chains of (TCP-PEG5K)(6)-Hb, 4 are conjugated to the alpha-amino groups of Hb, and the other 2 chains are distributed on epsilon-amino groups, identified as Lys-40(alpha) (approximately 45%), Lys-56(alpha) (approximately 25%), and Lys-8(beta) (approximately 24%). The studies with hamster infused with a bolus of a 4 gm % solution of (TCP-PEG5K)(6)-Hb equivalent to 10% of their blood volume have established that this new hexaPEGylated Hb is vasoinactive. The viscosity and the colloidal osmotic pressure of (TCP-PEG5K)(6)-Hb at 4% is 1.9 cP and 69.7 mmHg, respectively. The molecular radius of (TCP-PEG5K)(6)-Hb is about 4.6 nm and is significantly smaller than hexaPEGylated Hbs developed using other direct and extension arm facilitated PEGylation platform. The presence of an outside the central cavity intramolecular crosslink, succinimidophenyl-PEG2K between Cys-93(beta, beta') in (TCP-PEG5K)(6)-betabeta-Hb strongly impacts its solution properties. These patterns of influence suggest that the inter-dimeric interactions in (TCP-PEG5K)(6)-Hb is weakened just as with other direct PEGylation platforms, and (SP-PEG5K)(6)-Hb generated by EAF-PEGylation is unique in not inducing this effect. A comparison of the properties of hexaPEGylated Hbs establishes that rigidity of the conjugation linkage between PEG and Hb plays a significant influence on the resultant dictating solution properties and/structure/conformation of PEG-Hb adduct.
authors: Department of Physiology and Biophysics, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, NY, USA.
authors: Fantao
authors: F
authors: Meng
authors: Belur N
authors: BN
authors: Manjula
authors: Amy G
authors: AG
authors: Tsai
authors: Pedro
authors: P
authors: Cabrales
authors: Marcos
authors: M
authors: Intaglietta
authors: Paul K
authors: PK
authors: Smith
authors: Muthuchidambaram
authors: M
authors: Prabhakaran
authors: Seetharama A
authors: SA
authors: Acharya
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000187:drug effects*; D006224:Cricetinae; D006454:Hemoglobins / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D008297:Male; D008647:Mesocricetus; D010100:Oxygen / Q000737:chemistry; D010952:Plasma Substitutes / Q000737:chemistry* / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000494:pharmacology; D011485:Protein Binding; D014783:Viscosity
chemical_list: D006454:Hemoglobins; C109960:PEG-hemoglobin; D010952:Plasma Substitutes; D011092:Polyethylene Glycols; D010100:Oxygen