细胞功能测定

Among the currently available methods for gene transfer, recombinant murine retroviruses remain the best established method for achieving stable integration of a transgene with high efficiency. Pioneering work by a number of groups has demonstrated the feasibility of using this me ...

Since the mid-1980s, murine retroviral vectors have been used extensively by a number of investigators to clonally mark and genetically modify primitive hematopoietic stem cells (HSC) (1,2). During this period, both vectors and packaging systems used to generate virus have undergone c ...

This chapter provides information on the methods used to introduce genes into human hematopoietic stem and progenitor cells, using Moloney Murine Leukemia (MoMuLV)-based retroviral vectors. MoMuLV-based vectors have the ability to efficiently transfer genes into mammalian c ...

Lentiviral vectors based upon human immunodeficiency type I (HIV) are increasingly being used to transduce nondividing or terminally differentiated cells, despite the fact HIV is a known, lethal pathogen. This is because lentiviruses contain multiple gene products that allow infe ...

The events that determine whether hematopoietic stem cells (HSC) divide in the course of self-renewal or differentiate and become committed progenitor cells are regulated by specific gene expression. Although little is known of the molecular controls for these diverse events, the act ...

Recently, there has been much interest in the embryonic origins of the adult hematopoietic system in mammals (1). The controversy surrounding the potency and function of hematopoietic cells produced by the yolk sac compared to those produced by the intrabody portion of the mouse embryo has pr ...

The extracellular nucleases commonly called the BAL 31 nuclease take their name from the designation given the marine bacterium producing them, which was originally classified as Pseudomonas BAL 31 (1) and reclassified as belonging to the small genus Alteromonas (2) with the species nam ...

Ligases are a class of enzymes that catalyze the joining of nucleic acid molecules by the formation of phosphodiester bonds between their termini (1). The nucleic acid substrate to be linked may be DNA or RNA depending on the type of ligase involved.

Mung-bean nuclease 1 was first purified by Sung and Laskowski (1) in 1962 from mung-bean sprouts (Phaseolus aureus). It belongs to the class of enzymes EC 3.1.30.l., which has a preference for single-stranded nucleic acid substrates, lacks sugar specificity, and hydrolyzes single-stranded s ...

The term ribonuclease (RNase) is an imprecise term and is used to cover both enzymes that cause exonucleolytic cleavage and endonucleolytic cleavage of RNA. Exonucleases may cleave the RNA in 3′-5′ direction or vice versa, whereas some endoribonucleases have a specific requirement for cer ...

Pronase is the name given to a group of proteolytic enzymes that are produced in the culture supernatant of Streptomyces griseus K-1 (1–3). Pronase is known to contain at least ten proteolytic components: five serine-type proteases, two Zn2+ endopeptidases, two Zn2+-leucine aminopeptida ...

There are three main reasons why a protein chemist might wish to cleave a protein of interest into peptide fragments. The first reason is to generate, by extensive proteolysis, a large number of relatively small (5–20 residues) peptides either for peptide mapping (see vol. 1, Chapter 5) or for purific ...

Proteinase K is a serine protease and the main proteolytic enzyme produced by the fungus Tritirachium album Limber (1). The enzyme has abroad specificity, cleaving peptide bonds C-terminal to a number of amino acids. The enzyme is produced, together with other proteases and an aminopeptidas ...

Carboxypeptidases are proteolytic enzymes that remove L-amino acids, one residue at a time, from the carboxyl terminus of polypeptide chains, i.e., they are exoproteases. A number of such enzymes have been isolated from plant and animal sources, each differing in their chemical and physical ...

Aminopeptidases are proteolytic enzymes that remove L-amino acids sequentially from the amino termini of polypeptide chains. A number of aminopeptidases have been isolated, including leucine aminopeptidase from serine kidney cytosol (1), aminopeptidase P from E. coli (2), proli ...

Alkaline phosphatases (or alkaline phosphomonoesterases) catalyze the hydrolysis of phosphate monoesters of a variety of alcohol moieties, being most active at an alkaline pH. The enzymes have been isolated from a variety of sources, including bacteria, fungi, invertebrates, fish, ...

Enzymes able to digest nucleic acids are of course essential to molecular biology, indeed the whole technology was founded on the discovery of bacterial enzymes that cleave DNA molecules in a base-specific manner. These enzymes, the type II restriction endonucleases, are perhaps the best s ...

The enzyme polynucleotide kinase (PNK, or ATP:5′-dephospho-polynucleotide 5′-phosphatase) catalyzes the transfer of a γ-phosphate group from a 5′-nucleoside triphosphate moiety to a free 5′-hydroxyl of a polynucleotide such as DNA or RNA, to form a 5′-phosphorylated DNA or RNA molecule a ...

From Chapter 1 on nucleases, we know that the term DNase refers to an enzyme that endonucleolytically cleaves DNA molecules. This chapter deals with those DNases that preferentially catalyze the hydrolysis of double-stranded DNA (ds DNA) and that have found a use in the various techniques empl ...

Taq polymerase (EC 2.7.7.7) is a thermostable DNA-dependent DNA polymerase that was first isolated in 1976 from Thermus aquaticus strain YT-1 (ATTC # 25 104)(1). It catalyzes the template-directed polymerization of dNTPs at high temperatures. When Taq polymerase was isolated in 1976, nobody ...