Hepatocyte growth factor/scatter factor (HGF/SF) has a cofactor requirement for heparan sulfate (HS) and dermatan sulfate (DS) in the optimal activation of its signaling receptor MET. However, these two glycosaminoglycans (GAGs) have different sugar backbones and sulfation patterns, with only the presence of iduronate in common. The structural basis for GAG recognition and activation is thus very unclear. We have clarified this by testing a wide array of natural and modified GAGs for both protein binding and activation. Comparisons between Ascidia nigra (2,6-O-sulfated) and mammalian (mainly 4-O-sulfated) DS species, as well as between a panel of specifically desulfated heparins, revealed that no specific sulfate isomer, in either GAG, is vital for interaction and activity. Moreover, different GAGs of similar sulfate density had comparable properties, although affinity and potency notably increase with increasing sulfate density. The weaker interaction with CS-E, compared with DS, shows that GlcA-containing polymers can bind, if highly sulfated, but emphasizes the importance of the flexible IdoA ring. Our data indicate that the preferred binding sites in DS in vivo will be comprised of disulfated, IdoA(2S)-containing motifs. In HS, clustering of N-/2-O-/6-O-sulfation in S-domains will lead to strong reactivity, although binding can also be mediated by the transition zones where sulfates are mainly at the N-and 6-O-positions. GAG recognition of HGF/SF thus appears to be primarily driven by electrostatic interactions and exhibits an interesting interplay between requirements for iduronate and sulfate density that may reflect in part a preference for particular sugar chain conformations.

Bovine lactoferrin was separated into lactoferrin-a and lactoferrin-b from bovine colostrum. Lactoferrin-a was eluted at 0.38 M NaCl and lactoferrin-b was eluted at 0.43 M NaCl by carboxymethyl cation-exchange chromatography at pH 7.7, 0.05 M phosphate buffer. The molecular weights were estimated at 84,000 for lactoferrin-a and 80,000 for lactoferrin-b. Lactoferrin-a contents were 258.0 mg/L and lactoferrin-b contents were 524.3 mg/L of colostrum for cow 19. From colostrum to normal milk, total lactoferrin was from 17.1 to 129.4 mg/L during the normal lactational period; however, lactoferrin did not separate clearly into lactoferrin-a and lactoferrin-b. The lactoferrin-a measured from six cows was 258.0, 114.0, 112.8, 64.0, 59.7, and 22.4 mg/ L and the lactoferrin-b 524.3, 331.8, 184.7, 170.7, 129.3, and 44.0 mg/L, respectively. The average was 105.2 mg (31.3%) for lactoferrin-a and 230.8 mg (68.7%) for lactoferrin-b.

The rare N-unsubstituted glucosamine (GlcNH 3 ؉ ) residues in heparan sulfate have important biological and pathophysiological roles. In this study, four GlcNH 3 ؉ -containing disaccharides were obtained from partially de-N-sulfated forms of heparin and the N-sulfated K5 polysaccharide by digestion with combined heparinases I, II, and III. These were identified as ⌬HexA-GlcNH 3 and ⌬HexA-(2S)-GlcNH 3؉ (6S). Digestions with individual enzymes revealed that heparinase I did not cleave at GlcNH 3 ؉ residues; however, heparinases II and III showed selective and distinct activities. Heparinase II generated ⌬HexA-GlcNH 3 ؉ (6S), ⌬HexA(2S)-GlcNH 3 ؉ , and ⌬HexA-(2S)-GlcNH 3 ؉ (6S) disaccharides, whereas heparinase III yielded only the ⌬HexA-GlcNH 3 ؉ unit. Thus, the action of heparinase II requires O-sulfation, whereas heparinase III acts only on the corresponding non-sulfated unit. These striking distinctions in substrate specificities of heparinases could be used to isolate oligosaccharides with novel sequences of GlcNH 3 ؉ residues. Finally, heparinases were used to identify and quantify GlcNH 3 ؉ -containing disaccharides in native bovine kidney and porcine intestinal mucosal heparan sulfates. The relatively high content of O-sulfated GlcNH 3 ؉ -disaccharides in kidney HS raises questions about how these sequences are generated.

This work was performed to clarify the differences in glycan moieties between multiple molecular mass forms of bovine lactoferrins (bovine lactoferrins-a and -b). After digestion of both bovine lactoferrins with cyanogen bromide and V8 protease, glycopeptides were successively purified by concavalin A affinity chromatography and HPLC on an octadecylsilyl column. Four glycopeptides glycosylated at Asn-233, -368, -476, and -545 were obtained from both hydrolysates of bovine lactoferrins-a and -b. On the other hand, a glycopeptide glycosylated at Asn-281 was only detected in hydrolysate of bovine lactoferrin-a, indicating that bovine lactoferrin-a possessed five N-glycosylated sites. The glycan linked to Asn-281 of bovine lactoferrin-a was found to consist of fucose, galactose, and N-acetylgalactosamine in addition to mannose and N-acetylglucosamine. HPLC analysis of this glycan on a normal phase column showed that peaks of several glycans were detected. These glycans changed to one major glycan consisting of only mannose and N-acetylglucosamine on exoglycosidase digestion. From these results, this glycan seemed to be of the complex type and possess heterogeneous structure.

A superior Fe-containing MCM-22 zeolite prepared by one-pot synthesis method (OP-Fe/M22) showed excellent NH3 selective catalytic reduction (NH3-SCR) activity and almost 100% N2 selectivity in a wide temperature window (200–500...

Fe-Doped γ-Al2O3 porous hollow microspheres with hierarchical porosity were fabricated as efficient catalysts for H2S selective oxidation.

The NH3-SCR activities and hydrothermal stabilities of five xCu/MCM-22 zeolites with different Cu loadings (x = 2–10 wt%) prepared by incipient wetness impregnation method were systematically investigated. The physicochemical properties of xCu/MCM-22 zeolites were analyzed by XRD, nitrogen physisorption, ICP-AES, SEM, NH3-TPD, UV-vis, H2-TPR and XPS experiments. The Cu species existing in xCu/MCM-22 are mainly isolated Cu2+, CuOx and unreducible copper species. The concentrations of both isolated Cu2+ and CuOx species in xCu/MCM-22 increase with Cu contents, but the increment of CuOx species is more distinct, especially in high Cu loadings (>4 wt%). NH3-SCR experimental results demonstrated that the activity of xCu/MCM-22 is sensitive to Cu content at low Cu loadings (≤4 wt%). When the Cu loading exceeds 4 wt%, the NH3-SCR activity of xCu/MCM-22 is irrelevant to Cu content due to the severe pore blockage effects caused by aggregated CuOx species. Among the five xCu/MCM-22 zeolites, 4Cu/MCM-22 with moderate Cu content has the best NH3-SCR performance, which displays higher than 80% NOx conversions in a wide temperature window (160–430 °C). Furthermore, the hydrothermal aging experiments (xCu/MCM-22 was treated at 750 °C for 10 h under 10% water vapor atmosphere) illustrated that all the xCu/MCM-22 zeolites exhibit high hydrothermal stability in NH3-SCR reactions.

The presence of glycan at Asn-281 in bovine lactoferrin-a, which has a higher molecular weight than regular lactoferrin-b, was found in our previous study. The present work was performed to clarify the structures of the glycans linked to the five N-glycosylation sites in lactoferrin-a and to compare them with those of glycans linked to lactoferrin-b. In lactoferrin-a, the glycans linked to Asn-233 and Asn-545 were of the high-mannose type, whereas those present at Asn-368 and Asn-476 were complex-type ones. These glycans possessed heterogeneous structures. A comparative study of the glycans on bovine lactoferrin-a and bovine lactoferrin-b by HPLC showed that the structures of the glycans linked to Asn-368, Asn-476, and Asn-545 were very similar, the exception being the glycan linked to Asn-233. In addition, analysis of the structure of the glycan bound to Asn-281 present only in lactoferrin-a showed it possessed the heterogeneous structure of a complex-type glycan in which the structures Man3GlcNAc2, Man3GlcNAc4, Man3GlcNAc4Fuc are suggested to be present based on HPLC retention times only.