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T T Yip

Publications and source records attributed to T T Yip.

63 records · Page 4Linked to original sources
PubMed1985

Quantitative analysis of ginsenosides in fresh Panax ginseng.

TLC, DCC and HPLC were used to study the ginsenoside composition of the main root, lateral root, rhizome, leaves and seeds of Panax ginseng cultivated in Jilin, China. Each of these methods has advantages of its own and the ensemble reveal the special features of Jilin ginseng. Total saponin content of various plant parts in Jilin ginseng showed a mid-range value as compared to those in ginsengs reported in literature. Fresh as well as sun-dried specimens from the same batch possessed a high percentage of Rg1 in the main root and this might account for the traditional preference of this plant part despite its lowest percentage of saponin in the whole plant. Large amounts of polar saponins were also observed in roots and rhizome of fresh Jilin ginseng, the nature and significance of which remained to be investigated.

China↗
PubMedDate not supplied

Evaluation of peptide/metal ion interactions by UV laser desorption time-of-flight mass spectrometry.

A relatively recent method developed to determine the molecular weights of intact peptides and proteins, matrix-assisted UV laser desorption time-of-flight mass spectrometry (LDTOF-MS), has been evaluated as a new means to investigate the metal ion-binding properties of model synthetic peptides. A contiguous sequence of 25 residues on the surface of the 74 kDa human plasma metal-binding transport protein histidine-rich glycoprotein (HRG) has been identified as a bioactive metal-binding domain. The peptide, (GHHPH)5G, was synthesized and evaluated by LDTOF-MS before and after the addition of Cu(II) in solution with 2,5-dihydroxybenzoic acid as the matrix. In the absence of added Cu(II), the major protonated molecular ion (M + H)+ was observed to have a mass equal to its calculated mass (2904.0 Da). In the presence of Cu(II), however, five additional peaks were observed at mass increments of approximately 63.9 Da. The maximum Cu(II)-binding capacity observed for the 26-residue peptide (5 g-atoms/mol) suggested that up to 1 Cu(II) may be bound per 5-residue internal repeat unit (GHHPH) within this peptide; several other monovalent and divalent metal cations were not bound under identical conditions of analysis. The Cu(II)-binding stoichiometry was verified by spectrophotometric titration and by frontal analyses of the immobilized peptide with a solution of Cu(II) ions. These results demonstrate the ability to verify directly the solution-phase binding capacity of metal-binding peptides by LDTOF-MS.

Amino Acid Sequence↗
PubMedDate not supplied

Metal ion affinity adsorption of a Zn(II)-transport protein present in maternal plasma during lactation: structural characterization and identification as histidine-rich glycoprotein.

A high-affinity Zn(II)-binding protein has been purified to homogeneity (880-fold) from the plasma of lactating women by a single affinity adsorption step on columns of tris(carboxymethyl)ethylenediamine (TED)-agarose loaded with Zn(II) ions. Purity was evaluated by high-performance reverse-phase (phenyl) chromatography and by silver staining after SDS-polyacrylamide gradient gel electrophoresis. The mass of denatured Zn(II)-binding protein was estimated by SDS-polyacrylamide gradient gel electrophoresis to be 75 kDa under both reducing and nonreducing conditions; by matrix-assisted uv laser desorption time-of-flight mass spectrometry the purified protein mass was determined to be 66 kDa. The amino acid composition revealed a high content of His (13 mol%) and Pro (12 mol%). N-terminal amino acid sequence analysis (50 residues) identified the purified protein as histidine-rich glycoprotein (HRG). Immunoblots demonstrated the absence of fragments in the purified product. An enzyme-linked immunosorbent assay was developed; a 75% recovery of intact HRG from the immobilized Zn(II) ion affinity column was documented. The circular dichroism spectra for the purified human HRG in the far uv (260-178 nm) were similar to those published for human and rabbit serum HRG. These results demonstrate that TED-immobilized Zn(II) ions can be used as a new and efficient method for the isolation of structurally intact human plasma HRG.

Amino Acid Sequence↗
PubMedDate not supplied

Effects of Fructus gardeniae extract on hepatic function.

This article discusses the effects of Fructus Gardeniae extract on hepatic function. Fructus Gardeniae extract manifested no hepatotoxic effects on rats, as shown by alkaline phosphatase, aspartate aminotransferase, and lactate dehydrogenase studies. Fructus Gardeniae extract failed to activate the UDP-glucuronyltransferase system; whereas in hyperbilirubinemic state the enzyme was activated, presumably by substrate induction. Fructus Gardeniae extract increased the activity of UDP-glucose dehydrogenase, which would result in an increase in availability of UDP-glucuronic acid intracellularly, BSP clearance study showed an unexpected impairment of hepatic uptake of the dye after extract treatment. The action mechanism involved in lowering of serum bilirubin level by Fructus Gardeniae extract may well be complex; it is probably acting on a locus other than glucuronyl transferase.

Alkaline Phosphatase↗