Get answers to common questions about our catalog of PEG and activated polymer products.
I have a question about one of your products, who do I contact?
For a question regarding an order or how to place an order, contact us at sales@GannetBioChem.com.
How do I place an order?
You can place an order on our products page at www.catalog.gannetbiochem.com/products or by clicking on the products link in the menu. You can also email orders or questions to sales@GannetBioChem.com.
What are the storage conditions for the products?
Because PEG reagents are temperature, air, and moisture sensitive they should be stored in a freezer at or below -10C upon receipt. Please allow PEG reagents to equal room temperature before opening. We recommend storing our PEG reagents as the dry, powder form only and not in any type of solution. Each time the bottle is opened it will need to be backfilled with an inert gas (i.e. argon, nitrogen) and tape the lid before being stored again.
If your reagent requires rebottling please follow these steps:
- Allow reagent to equilibrate to room temperature
- While reagent is thawing, prepare glove box or another suitable area for packaging which will allow for an inert atmosphere
- Flush the repackaging enclosure with an inert gas (i.e. argon, nitrogen)
- Repackage into desired aliquots
- Flush each aliquot with inert gas before closing and tape the lid
- Store each aliquot at or below -10C until ready to use
If you do not have the proper equipment to rebottle, we offer a bottling service at $50 setup fee and $5.00 a bottle. This service must be ordered at the time you place your order.
Please note that acrylate products are light sensitive and need to keep light exposure to a minimum.
How do you ship your reagents?
We ship all of our reagents at ambient temperature for overnight delivery in the United States and Priority International for international orders, most international shipments arrive within 3-4 days. These methods are used for the stability of our products. You will receive an email with tracking number so you can track your shipment. Cold packs may be used during the hot summer months which may increase shipping cost due to increased weight.
The product you receive is bottled using argon gas to cover the product which prevents oxygen and moisture from getting to the product. For extra protection we then put in an enclosed bag with a desiccant. Because of this we are able to experience shipping delays without loss of reactivity to our products. Please use the storage instructions we sent with your product to prolong the life of the product; this is critical.
Do you offer compliant (cGMP) manufacturing?
We have established our Quality System and are manufacturing cGMP compliant “Bulk Pharmaceutical Chemical” reagents. We welcome all discussions regarding this service and will work with you to help our products fit your project requirements. Call today to request a quotation or to schedule a conference call. We offer many products already manufactured as cGMP and can move most catalog products to cGMP. We welcome customer audit and recommend Manufacturing and Supply Agreements for cGMP customers.
Do I need compliant (cGMP) products or catalog- (research-grade) products?
Click here to read more about the differences between compliant- and catalog-grade products.
Do you offer consulting services?
Laysan Bio has been acquired by Gannet BioChem, and our combined capabilities include consulting services for your current and future PEG programs. You can get more details on the Gannet BioChem website.
How do I get the structures for your products?
If there is not a structure posted for the reagent you are interested in on our website under products, MSDS, or SDS, please contact us at sales@GannetBioChem.com for structure information.
How do I get an MSDS or SDS?
A copy of CoA and SDS/MSDS will be sent with your shipment. If you need a copy prior to ordering you can find catalog MSDS Documents page or SDS Documents page.
What is the difference between your ester reagents, SCM and SC?
SCM
- Hydrolysis half-life is 0.75 (minutes) at pH8, 25°C
- Amide linkage
- Faster conversion
- Good conversion in organic; not good in aqueous
SC
- Hydrolysis half-life is 20.4 (minutes) at pH8, 25°C
- Urethane or carbamate linkage
- Longer reaction time
- Slower hydrolysis
- Good in organic; also works in aqueous
Do you have more information on your SVA reagents?
Click here to download more information regarding our popular SVA reagents.
What is the half-life information for your ester reagents?
Click here to download information regarding the half-lives of our esters.
Which reagents are amine reactive and what is the difference between them?
The end groups that are reactive with amine are listed below and they are in two different categories, permanent linkage and degradable linkage
PERMANENT: NPC, SC, SVA, SAS, BALD
DEGRADABLE: SS, SG
How do I deprotect the BOC and FMOC reagents?
Protocol to Deprotect BOC
Standard BOC Amino Acid Deprotection
50% (v/v) TFA/DCM; 50 minutes at room temperature
Follow with washings with 5% (v/v) DIPEA/DCM to remove TFA
Protocol to Deprotect FMOC
Standard FMOC Amino Acid Deprotection
Place the FMOC protected product in a round bottom flask and add 20% (v/v) piperdine in DMF(approximately 10ml/gm resin)
Shake the mixture at room temperature for 30 minutes
Filter the FMOC protected product and wash it with several portions of DMF
What is PEG’s solubility?
PEG in all molecular weights are soluble at concentrations less than a 50:50 w/w concentration in water and other solvents.
PEGs are readily soluble in dichloromethane, chloroform, acetonitrile, and water at room temperature.
PEGs require heat to be soluble in toluene, methanol, ethanol, and isopropanol.
PEGs are not soluble in ethers, ethylene glycol, hexane, and are not soluble in most alcohols at room temperature.
If you need an organic solvent, dichloromethane and acetonitrile are two good choices.
What is the difference between butyraldehyde and propionaldehyde?
The propionaldehyde is a little more reactive than the butyraldehyde so the reaction with the butyraldehyde should be allowed to mix about 2 hours longer.
Both propionaldehyde and butyraldehyde will form a secondary amine when reacted and will work in the same solutions. The butyraldehyde has one more methylene between the PEG and aldehyde functionality that the propionaldehyde.
What are the disadvantages to the PEG aldehydes? What is the advantage to the ButyrALD?
Propionaldehyde PEG reagents involve coupling challenges to proteins due to formation of undesirable side-products necessitating extensive purification to obtain pharmaceutical grade product.
ButyrALD overcomes these challenges by being more selective and stable during coupling to biological agents. ButyrALD’s increased selectivity allows preferential coupling with specific amino groups; and in particular, may lead to a greater selectivity for N-terminal amino groups on proteins and peptides.
The Maldi spectrum of PEG-DSPE product shows PEG without DSPE peak as a major peak. Is this evidence that DSPE is not connected to the PEG in the product?
The DSPE part cleaves easily even with mild ionization techniques. It is common to see the PEG fragment as a major peak in the spectrum. This is not evidence that the DSPE is not connected to the PEG in the product. Connectivity is proven by NMR.
Determining molecular weight (MW) for phospholipid products
We report a theoretical MW for phospholipid products. The theoretical molecular weight is determined by adding the known MW of the PEG plus the weight of the phospholipid. We determine the Mn on the starting PEG by NMR, which is reported on the CoA, then the MW of the end groups are added which gives the theoretical molecular weight. Phospholipids are harmful to the GFC columns therefore Laysan does not run GFC on any of our phospholipid products and MALDI can cleave the fatty esters from the phospholipid due to the ionization strength of the method, therefore resulting in a lower molecular weight.
How do I calculate density of PEG reagents?
This is only accurate for molecular weights below 1,000. Take a syringe and draw up 1ml then weigh product. Density = Mass over Volume.
What is the physical distance within the PEG?
BOND LENGTH
C-C is 154 pm (0.154 nm)
C-O is 143 pm (0.143 nm)
Which PEG should I use?
Reagent selection, linkage, and stability (under physiological conditions) for PEGylation.
| Carboxyl PEGylation (Nucleophilic PEGs) | Linkage Formation |
|---|---|
| MPEG-AMINE and a coupling agent | Amide (stable) |
| MPEG-ALCOHOL and a coupling agent | Ester (subject to hydrolysis) |
| Amine PEGylation (Electrophilic PEGs) | |
| MPEG-Ester | Amide (stable) |
| MPEG-Carbonate | Urethane (stable) |
| MPEG-Aldehyde and a reducing agent | Secondary amine (stable) |
| MPEG-Aldehyde acetal and a reducing agent | Secondary amine |
| Thiol Reagent PEGylation | |
| MPEG-MALEIMIDE | Sulfide (stable) |
| MPEG-THIOL | Disulfide (can be reduced) |
Protein PEGylation reaction conditions vary depending on the protein, the desired degree of PEGylation, and the PEG reagent. Factors to consider in the choice of a PEG reagent are:
(1) the desired point of attachment (amine, thiol, carboxyl, etc.)
(2) hydrolytic stability, activity, pharmacokinetics, PEG-isomers, and immunogenicity of the derivative
(3) suitability for analysis
Additional information can be obtained from the following sources:
General Discussions: (a) “Poly(Ethylene Glycol) Chemistry: Biotechnical and Biomedical Applications,” J.M. Harris, Ed., Plenum, NY, 1992, Chap. and (b) “Poly(ethylene glycol) Chemistry and Biological Applications,” J.M. Harris and S. Zalipsky, Ed., ACS Symposium Series 680, 1997.
How can free PEG be detected?
Free PEG can be detected by SDS-PAGE using barium iodide stain.
Manfred M. KurfUrst, Analytical Biochemistry 200, 244-248 (1992).
This paper gives the recipe for the stain. The stain can be washed out with water and then the protein stained with Coomassie Blue.
Free PEG can also be detected by SEC HPLC using an RI detector.
Regarding polydispersity (molecular weight distribution)
NOTE: All of our PEGs have a polydispersity of less than 1.07.
All of our PEGs have some variance in the number of ethylene oxide units. This is a result of anionic polymerization. Polydispersity (PDI) is a ratio that represents the broadness of a molecular weight distribution. PDI is the ratio of the number average molecular weight (Mn) to the weight distribution. PDI is the ratio of the number average molecular weight (Mn) to the weight average molecular weight (Mw) (PDI = Mw/Mn). If the PDI is equal to 1, then Mn equals Mw and the polymer is said to be monodisperse. In real life, polymers are not truly monodisperse (except for natural proteins), although PEGs made anionically do have a low PDI (1.01 – 1.05). As Mn changes with Mw, the PDI changes (it will always be greater than 1).
What are the conditions for covalently linking PEG to a silicon dioxide or quartz glass surface?
Possible candidates should have an electrophilic group (like aldehydes, active carbonates, etc.) for the surface coating of quartz and modified quartz. A useful reference would be Chapter 24 in the ACS Symposium Series 680 book “Poly(ethylene glycol) Chemistry and Biological Applications” edited by J. Milton Harris and S. Zalipsky. Pages 390 and 391 (“Effect of PEG Functional Group and MW on PEG-modified Quartz”) might be more specific to the your needs.
AN EXAMPLE:
The process of pegylation of silicon/glass surfaces with mPEG-silane can be, for example (reference: Desai et al., Business Briefing: Medical Device Manufacturing and Technology, 2002), conducted as follows. The silicon/glass surfaces are first cleaned by treatment with 1:1:5 ratio of 25% ammonia, 30% hydrogen peroxide, and deionized water for 15 minutes at 80 Celsius. This is followed by treatment with 1:1:6 ratio of 50% hydrogen chloride, 30% hydrogen peroxide, and deionized water for 15 minutes at 80 Celsius. The surfaces are then rinsed with distilled water and dried with nitrogen gas. Alternatively, surfaces can be cleaned with acetone and isopropanol for 5 min. each, then activated in concentrated HNO3 for 3 min. followed by extensive rinsing with water (Biomaterials, 23(2002):893-900). The surface modification with mPEG-silane can be carried out by immersing the surface in freshly prepared solution of 2 mg/mL of mPEG-silane for 1 hour, followed by rinsing with corresponding solvent and drying with nitrogen gas.
Protocol for attaching PEG to a glass surface:
Nature, Vol 419 (October 10, 2002), page 638.
Protocol for coating gold surfaces?
A useful reference would be Chapter 23 in the ACS Symposium Series 680 book, “Poly(ethylene) glycol Chemistry and Biological Applications” edited by J. Milton Harris and S. Zalipsky (“Using Self-Assembled Monolayers that Present Oligo(ethylene glycol) Groups to Control the Interactions of Proteins with Surfaces”).
Protocol for General Coating
A useful reference would be Chapter 24 in the ACS Symposium Series 680 book, “Poly(ethylene glycol) Chemistry and Biological Applications” edited by J. Milton Harris and S. Zalipsky (“Electrokinetic Analysis of Poly(ethylene glycol) Coating Chemistry”).
What are the sulfhydryl (SH) selective PEG reagents?
Maleimides
Thiols
These reagents have both been utilized for coupling to the free sulfhydryl group of cysteines present in proteins.