Sugar oxazoline derivatives are useful donor substrates for N-acetylglucosaminidase-catalyzed glycosylation reactions. In this review, we describe the direct conversion of free sugars to their oxazoline derivatives by using water-soluble dehydrating agents and its application to enzymatic synthesis of complex glycosidic compounds including glycoproteins.

View full abstract

Human Induced pluripotent stem cells (hiPSCs) and embryonic stem cells (hESCs) gain great attentions as cell sources for regenerative medicine. Since hiPSCs and hESCs have ability to grow eternally (self-renewal) and to differentiate into any types of cells comprising human body (pluripotency), even a small number of cells could form teratoma inside recipients. To solve this subject, I have focused on cell surface glycans of hiPSCs and hESCs. In 2007, just after hiPSCs were developed, I performed comprehensive glycome analysis of hiPSCs derived from various origins. I could not only clarify structural features of cell surface glycans of hiPSCs/hESCs, but also discover a lectin, called rBC2LCN, which is specific to hiPSCs/hESCs. rBC2LCN was also named as AiLecS1, since this lectin was the first lectin specific to stem cells developed at AIST (rBC2LCN/AiLecS1). Based on this finding, I developed two technologies to provide solutions to the tumorigenicity of hiPSCs/hESCs. One is the GlycoStem test to quantitate hiPSCs/hESCs using cell culture supernatants and another is a drug conjugate of rBC2LCN/AiLecS1 to eliminate hiPSCs/hESCs. In this review, I describe the discovery of rBC2LCN/AiLecS1 and its installation to regenerative medicine.

View full abstract

Influenza A virus (IAV) has two envelope glycoproteins, hemagglutinin (HA) and neuraminidase (NA). HA recognizes sialic acids at the terminals of glycan chains on the host cell surface as virus receptors. NA shows sialidase activity, which cleaves sialic acids from the terminals of glycan chains. The viral sialidase activity is well-known to facilitate release of progeny virus from the host cell surface by preventing virus binding to sialic acid. Low-pH stability of viral sialidase activity is a unique property for pandemic IAV NAs distinct from most epidemic IAVs. It is thought that the low-pH stability of sialidase activity contributes to the spread of infection in a pandemic of a new subtype of IAV through enhancement of virus replication. Recently, a new sialidase substrate has been developed for histochemical fluorescent visualization of viral sialidase activity. This substrate can visualize living IAV-infected cells abundantly expressing viral NA by an easy protocol in a short time. The properties and functions of IAV sialidase activity, mainly in terms of low-pH stability, and a new tool for detection of IAV sialidase activity are described in this review.

View full abstract

Sugar oxazoline derivatives are useful donor substrates for N-acetylglucosaminidase-catalyzed glycosylation reactions. In this review, we describe the direct conversion of free sugars to their oxazoline derivatives by using water-soluble dehydrating agents and its application to enzymatic synthesis of complex glycosidic compounds including glycoproteins.

View full abstract

Human Induced pluripotent stem cells (hiPSCs) and embryonic stem cells (hESCs) gain great attentions as cell sources for regenerative medicine. Since hiPSCs and hESCs have ability to grow eternally (self-renewal) and to differentiate into any types of cells comprising human body (pluripotency), even a small number of cells could form teratoma inside recipients. To solve this subject, I have focused on cell surface glycans of hiPSCs and hESCs. In 2007, just after hiPSCs were developed, I performed comprehensive glycome analysis of hiPSCs derived from various origins. I could not only clarify structural features of cell surface glycans of hiPSCs/hESCs, but also discover a lectin, called rBC2LCN, which is specific to hiPSCs/hESCs. rBC2LCN was also named as AiLecS1, since this lectin was the first lectin specific to stem cells developed at AIST (rBC2LCN/AiLecS1). Based on this finding, I developed two technologies to provide solutions to the tumorigenicity of hiPSCs/hESCs. One is the GlycoStem test to quantitate hiPSCs/hESCs using cell culture supernatants and another is a drug conjugate of rBC2LCN/AiLecS1 to eliminate hiPSCs/hESCs. In this review, I describe the discovery of rBC2LCN/AiLecS1 and its installation to regenerative medicine.

View full abstract

Influenza A virus (IAV) has two envelope glycoproteins, hemagglutinin (HA) and neuraminidase (NA). HA recognizes sialic acids at the terminals of glycan chains on the host cell surface as virus receptors. NA shows sialidase activity, which cleaves sialic acids from the terminals of glycan chains. The viral sialidase activity is well-known to facilitate release of progeny virus from the host cell surface by preventing virus binding to sialic acid. Low-pH stability of viral sialidase activity is a unique property for pandemic IAV NAs distinct from most epidemic IAVs. It is thought that the low-pH stability of sialidase activity contributes to the spread of infection in a pandemic of a new subtype of IAV through enhancement of virus replication. Recently, a new sialidase substrate has been developed for histochemical fluorescent visualization of viral sialidase activity. This substrate can visualize living IAV-infected cells abundantly expressing viral NA by an easy protocol in a short time. The properties and functions of IAV sialidase activity, mainly in terms of low-pH stability, and a new tool for detection of IAV sialidase activity are described in this review.

View full abstract