|Date: September 14, 1998||Catalog Peptide Providers Table|
In the last 20 years or so, numerous peptides with a diverse array of biological activities have been identified. In the same time period, the advent of automated peptide synthesis has made these reagents cheap and easy to produce in large quantities. These developments have created a new class of research reagents, known as biologically active peptides. Many biologically active peptides occur naturally; however, many others have been designed to have specific activities--often modeled on the functional regions of characterized proteins.
Many naturally occurring peptides function as hormones, playing a role in activating or regulating various cellular pathways. For example, somatostatin, a 14 amino-acid peptide, binds to G-protein receptors on cell surfaces and inhibits the release of numerous physiological compounds, including insulin, glucagon, gastrin, and secretin. This peptide also functions as a neurotransmitter and recently received notoriety when it was shown to have an inhibitory effect on tumor angiogenesis. Other examples of regulatory peptides are endothelin, a potent contractor of smooth muscle, and oxytocin, a reproductive hormone that is essential for uterine contractions during labor.
Fluo-PeptideTM Image courtesy of Advanced Bioconcept
|Courtesy of Sigma Chemical Company|
Arg-Gly-Asp: Tripeptide from the cell-attachment domain of fibronectin.
Numerous peptide protease substrates and inhibitors are commercially available. Like the kinase/phosphatase substrates, most of the protease substrates consist of short peptides that correspond to a protease recognition sequence. However, for detection purposes, either a fluorogenic precursor, often a coumaryl or xanthyl derivative, or chromogenic compounds, such as p -nitroanilide, are conjugated to the peptide substrate. Cleavage by the protease results in either a fluorescent byproduct or a spectrally shifted chromophore. The inhibitors for the proteases can be made from peptides that have the same amino acid recognition sequence as the substrate but are conjugated to a chemical compound, usually an aldehyde or ketone, that interrupts the catalytic process. The inhibitors bind to the active site of the protease and inactivate the protease. A plethora of protease substrates and inhibitors is available for different metallo, cysteine, and serine proteases. Currently, applications for these reagents include use in apoptosis research to measure or inhibit the activity of the various caspase proteases (such as ICE and CPP32) and HIV research to look at HIV protease activity.
Many naturally occurring peptides, which are usually made in vivo by proteolytic cleavage, are relatively large--often 50 amino acids or more-- and often contain one or more disulfide bonds. This can make them difficult to produce, since manufacturing peptides longer than 60-70 amino acids really pushes the synthesis technology and, in the words of one core-facility manager, "it becomes a research project in itself." Another factor that can complicate synthesis is the specific amino acid residues that comprise the peptide. For example, residues such as tryptophan and methionine have lower coupling efficiencies, so peptides with many of these residues will have lower yields than peptides containing residues with better coupling efficiencies.
Peptide reagents are available from a diverse array of suppliers. Most of the suppliers fit into two broad categories: those that have a business built around the peptide synthesis technology and those that have built a business around supplying reagents to specific research areas.
Many custom peptide companies have expanded their business to offer a line of catalog peptides. The list of these companies includes American Peptide, AnaSpec, Bachem, Novabiochem, Peninsula Labs, Peptides International, Phoenix Pharmaceuticals, QCB, and Sigma/Aldrich. These companies have large catalogs of stock peptides in addition to thriving custom synthesis businesses. Peptides are included in the catalogs primarily as a result of their popularity. The catalogs usually list several hundred to a few thousand peptides across a spectrum of types. Since researchers often use antibodies to identify proteins of interest in the same studies in which many of the peptide reagents are used, some of these companies also offer a collection of antibodies to complement their peptide product lines. For the most part, these companies make all their own peptides and have an extensive technical understanding of peptide chemistry, both of which help insure quality. However, the companies sometimes have limited experience and understanding of the research applications for the peptides.
In a technology approach that is slightly different from that of the other peptide companies, Advanced Bioconcept, Enzyme Systems Products, and OncoImmunin have built businesses based on peptide-modifying techniques. Enzyme Systems Products has developed expertise in modifying peptides to make them useful protease substrates and inhibitors. Advanced Bioconcept has developed a proprietary technology to fluorescently label receptor-binding peptides in a manner that maintains biological activity of the peptide and does not interfere with receptor binding.
The second group of companies includes those that offer peptides as reagents as part of diverse lines of products for particular areas of research. These companies include names such as ALEXIS, American Qualex, BIOMOL, Calbiochem, CLONTECH, Kamiya, Promega, and Upstate Biotechnology, which offer peptide reagents as part of a spectrum of research reagents. Depending on their size, the companies may be more broad or focused in the research areas to which they market. However, for the most part, they all attempt to provide researchers in a particular area with a "one-stop shop" for all their reagent needs. In addition to peptides, a researcher can purchase antibodies, basic chemical compounds, inhibitors, labels, and so on. Often, these companies do not make all their own reagents but work with a variety of vendors to obtain a comprehensive line of products. However, since they often deal in large volumes, they may offer very similar pricing as companies that manufacture the reagents themselves.
Advanced Bioconcept, based in Montreal Canada, offers Fluo-peptides™--peptides fluorescently labeled using a proprietary technique that ensures a receptor-binding peptide maintains a high affinity for its receptor. The company's unique approach produces fluorescent probes for the study of peptide-receptor interactions in cellular imaging, flow cytometry, and drug screening applications. Paul Chipperton, marketing and sales manager, asserted that Advanced Bioconcept can "put any fluorescent label on a ligand peptide and guarantee the peptide maintains biological activity and high affinity for its receptor."
This five-year-old San Diego based company offers numerous antibodies, peptides, and other chemical reagents primarily for signal transduction and related areas of research. ALEXIS offers a comprehensive line of peptides, ranging from receptor-binding peptides to kinases and caspase substrates and inhibitors, that would interest researchers looking at signal transduction and related areas, such as apoptosis, nitric oxide regulation, and neurochemistry. Dr. Malu Polanski, the technical product manager, sees the company's expertise as primarily in offering comprehensive lines of biochemicals in targeted research areas. The manufacture of most of the peptide reagents is subcontracted.
American Peptide Company
For over 10 years, the American Peptide Company (APC) in Sunnyvale, Calif, has focused on providing catalog peptides, custom peptides, and peptide synthesis reagents for research and clinical applications. The company currently has a strong custom business, and offers over 1,000 presynthesized biologically active peptides directed toward popular areas of research. A majority of these catalog peptides, which are synthesized in-house, have a purity level greater than 98 percent. According to technical sales representative Chris Gothard, APC offers expertise on the design, characteristics, and handling of its custom and catalog peptides. Gothard also mentioned that APC provides GMP-grade peptides for clinical trials.
Cholinergic cell line demonstrating internalization of Fluo-neurotensinTM. Image courtesy of Advanced Bioconcept
Founded 18 years ago, this small company in San Clemente, Calif., offers a number of reagents, especially antibodies, that are of interest to researchers in signal transduction and neuroscience. Several peptides are offered as part of these reagent lines. American Qualex also offers custom peptide and recombinant protein purification services. According to president Dan Moothart, all of the peptide reagents are made in-house.
AnaSpec, based in San Jose, Calif., offers a broad range of peptides, as well as its custom peptide service. According to Dr. Anita Hong, the company president, AnaSpec specializes in "synthesizing long peptides, peptoids, chromogenic substrates, and peptides containing unusual amino acids." Many of these specialized peptides are useful as enzyme substrates/inhibitors or have an increased in vivo half-life. New peptides the company will be introducing in the near future include hepatitis C virus substrates, orexins, and various phosphopeptides.
Bachem, a worldwide peptide and biochemical manufacturer headquartered in Switzerland, has been in business for 27 years and is the leading manufacturer of bulk peptide reagents. Much of Bachem's business is directed toward supplying GMP-grade peptides for pharmaceutical and diagnostic uses. Bachem offers a large variety of receptor-binding peptides, as well as substrates and inhibitors. U.S. sales and marketing administrator Jane Love feels that the principal benefit Bachem offers to its research customers is its experience and expertise in the manufacturing of peptides. When asked about the purity level of its peptides, Love mentioned that each peptide has its own minimum criteria for purity, and it is not possible to define one purity standard across the board for all the peptides. Bachem continues to expand its peptide reagent product line and is introducing new metalloprotease and ICE protease substrates and inhibitors.
BIOMOL Research Laboratories, Inc.
A mid-sized Plymouth Meeting, Pa.-based company, BIOMOL offers a variety of reagents for the study of signal transduction and related areas. Its peptide reagents are included with a variety of other chemical compounds, bioactive lipids, and neuropharmacologics reagents. Ira Taffer, vice president of BIOMOL, emphasized that the company tries to offer a complete product line to offer researchers flexibility in their studies. Some of BIOMOL's peptides are made in house, while others are contracted out.
|Courtesy of Sigma Chemical Company|
Substance P Peptide
As a very large reagent company, Calbiochem, located in San Diego, Calif., epitomizes the one-stop-shop approach. Calbiochem offers reagents across the spectrum from chemical compounds to antibodies and kits. Margaret Dentlinger, the product manager for bioactive peptides, also added that the ability to cross- market the additional products of Calbiochem's sister companies, Novabiochem, Oncogene, and Nogagen, further enhances Calbiochem's ability to offer a very extensive selection of reagents to customers. Bioactive peptides, which are mostly protease and kinase substrates and inhibitors, make up a significant portion of the reagents Calbiochem offers, especially in the signal transduction product area. Dentlinger pointed out that Calbiochem tries to group the products according to functional categories. For example, it has compiled a complete catalog specifically for reagents that are useful to signal transduction researchers. Many of Calbiochem's products are obtained from the four brand headquarters as well as small contract vendors. Dentlinger sees this as an advantage because it enables her company to be responsive to researchers, needs and rapidly offer new "cutting-edge" products.
This Palo Alto, Calif.-based company offers a large line of products for molecular biology research. As part of its apoptosis product line, CLONTECH offers several kits, that use chromagenicly and fluorescently labeled peptide substrates to detect caspase protease activity. In addition, the company offers several caspase inhibitors. According to product manager Traci Yerby, CLONTECH is focusing on providing a breadth of quality products for apoptosis researchers and can provide more applications information and support than companies not focused in this area.
Enzyme Systems Products
This company, based in Livermore, Calif., specializes in synthetic protease substrates and inhibitors. Enzyme Systems Products peptide substrates are conjugated to either a fluorescent or colorimetric reagent, which allows two methods to detect a specific protease activity. Enzyme Systems also offers either reversible or irreversible inhibitors for specific proteases. Steve Panken, vice president of sales and marketing, mentioned that Enzyme Systems has a patent on its irreversible protease inhibitor peptides that are conjugated to fluoromethylketone.
In addition to some diagnostic products, Kamiya, based in Seattle, Wash., offers a range of antibodies, reagents, and kits for researchers in signal transduction, apoptosis, and DNA damage/repair. As part of its apoptosis line, Kamiya offers a number of caspase protease substrates and inhibitors, which Douglas Palmer, the scientific director, described as "in demand."
Since its inception over 14 years ago, Novbiochem, in San Diego, Calif., has grown to be one of the largest manufacturers of reagents for peptide synthesis and combinatorial chemistry. Novabiochem also offers an extensive line of biologically active peptides, provided under GMP and ISO 9001 manufacturing conditions for life science applications. According to Sven Wagner, director of sales for Novabiochem, the company is known for providing leading-edge solutions to its customers in the pharmaceutical, biotechnology, and research communities, with strong technical support and customer service.
OncoImmunin, Inc., based in Rockville, MD, is a small biotech company specializing in the design, synthesis, and sale of exciton-based fluorogenic protease substrates. The Company's patented technology enables peptide substrates to be cell-permeable, thereby allowing measurement of proteolytic activities in living cells; additionally, incorporation of amino acid sequence information from both sides of the protease cleavage site permits three-dimensional recognition rather than the more common linear mode. In the future the Company will be extending its patented technology into the areas of detection of other classes of enzymes, e.g., nucleases and glycosidases, as well as inhibitors.
Peninsula Laboratories, Inc.
Having been in business since 1976, Peninsula Labs, a company just south of San Francisco in San Carlos, Calif., is one of the original peptide synthesis companies. In addition to peptides, Peninsula offers a line of peptide synthesis reagents, some antibody products, and DNA labeling kits. Peninsula offers a catalog of over 2,000 presynthesized peptides, as well as a custom service. According to Mohammed Anwer, vice president of peptide manufacturing and process development, Peninsula considers itself a leader in the peptide market and is interested in pursuing the large-scale GMP manufacturing of peptide therapeutics. Peninsula continues to introduce catalog peptides as a service to its research customers and as a means to build relationships with researchers that may be looking for large-scale GMP production contracts down the line. Anwer also pointed out that, being a large-scale peptide manufacturer, Peninsula can offer economic benefits to customers, as well as high quality. He mentioned that a number of other companies have many of their peptide reagents manufactured by Peninsula.
Peptides International, a 15-year-old company in Louisville, Ky., focuses largely on complex, biologically active peptides. In addition to its custom business, Peptides International offers a range of presynthesized peptides, many of which have been made by the step-wise solution synthesis (rather than solid-phase) method, developed by the Peptide Institute in Osaka, Japan. According to DeAnna Long, director of marketing, Peptides International is particularly expert in the manufacturing of complex peptides, pseudopeptides, and combinatorial peptide libraries. For example, Long points out, "a number of the biologically active toxins have disulfide bonds which have to be introduced correctly after synthesis." Long emphasized the quality of peptides by noting that all the company's peptides produced by the solution method are greater than 98 percent pure and lack deletions and truncations often seen with long peptides. She also emphasized that Peptides International values technical support and attempts to provide customers with as much background and technical information as possible so customers can make knowledgeable decisions about how to best use the peptides in their research.
|Courtesy of Sigma Chemical Company|
Biologically Active Peptide
Phoenix Pharmaceuticals, a peptide company in the San Francisco, Calif., area founded 4 years ago by scientists that left Peninsula Labs, offers a variety of peptides, antibodies, and some immunoassays. In addition to a custom peptide service, Phoenix has an extensive catalog of over 3,000 different peptides. Eng Tau, the chief operating officer, confidently asserted that knowledge and expertise about peptides and peptide synthesis is the defining characteristic of Phoenix Pharmaceuticals. She mentioned that this expertise is particularly important when dealing with difficult or exotic peptides, but she felt customers using any peptides expect a high level technical expertise. Tau also mentioned that Phoenix very aggressively pursues the introduction of new peptides.
Promega, based in Madison, Wis., markets reagents for life science research as well as cell signaling assays. Its cell signaling product line provides peptide substrates, including biotinylated peptides, for protein kinases and phophatases; protein kinase-A, C, and G; tyrosine kinase; cdc2 kinase; and DNA-dependent protein kinase. Promega's line of serine/threonine phosphatase and tyrosine phosphatase assay systems include phosphorylated peptides to enable nonradioactive measurements of phosphatase activity. Labeled caspase substrates and inhibitors are also offered. According to product manager Pam Guthmiller, Promega has focused on these particular peptide reagents because they are of interest to a broad range of researchers in cell signaling.
Quality Controlled Biochemicals
In addition to providing a custom peptide service, the Massachusetts-based Quality Controlled Biochemicals (QCB) manufactures and sells primarily antibodies and peptides. QCB markets a wide variety of bioactive phosphorylated and cell-permeable peptides for neuroscience, signal transduction, apoptosis, and cell biology research. According to Julie Szabo, technical support manager, "QCB offers a comprehensive line of products for Alzheimer's disease, including over 35 beta-amyloid peptide analogs."
Sigma/Aldrich, a worldwide research reagent supplier based in St. Louis, Mo., offers an extensive line of biologically active peptides, manufactured and marketed under the Sigma, Fluka and RBI brands, as well as custom peptide synthesis and a complete line of peptide synthesis reagents. According to product manager Roy Winkel, Sigma markets approximately 3,500 peptides for applications in several research areas, including neuroscience, signal transduction, apoptosis, and calcium mobilization pathways. Michael Carelli, the RBI marketing and customer service manager, noted that just the RBI division offers approximately 150 different neuropeptides, which are supported with extensive and detailed references and recent studies. Winkel noted that "many of the products are cell-culture tested so they are known not to kill cells." He sees this as a major advantage of Sigma/Aldrich peptides, since many researchers use the peptides in cell culture assays. Winkel also mentioned the breadth of the product line and economic pricing as two additional benefits Sigma/Aldrich offers, and he estimated that the majority of the peptide reagents are made in house.
Upstate Biotechnology Inc.
Upstate Biotechnology in Lake Placid, N.Y., markets products, primarily antibodies, for signal transduction research. However, product manager Dr. Bill Beyer notes that the company offers a number of peptide substrates useful to researchers investigating signal transduction kinase cascades. Some of these are made in house, while the manufacturing of others is subcontracted. Among the new products offered by Upstate Biotechnology are Akt/PKB substrate peptide; fluorometric substrate peptides for caspase 1/ICE, 3/Apopain, and Caspase 8; PKC substrate and inhibitor peptides; and a number of specifically acetylated histone peptides.
Paul Diehl is a freelance writer based in Perth Amboy, N.J. He can be reached at firstname.lastname@example.org