Protein Loading and Sample Buffers
Select See the table below
- See the table below
Protein Loading and Sample Buffers
This is a category page, not a product page — pick the buffer that matches your gel system and click View to open its product page. The selection reference, applications, and FAQ follow below.
| Name | Tracking dye | Cat. No. | Size | Product Page |
|---|---|---|---|---|
| SDS Gel Loading Buffer | Bromophenol Blue | DCP-SDSLB5X | 5 x 1 mL | Viewarrow_forward |
| Native Loading Buffer | Bromophenol Blue | DCP-NLB5X | 20 ml | Viewarrow_forward |
| LDS Sample Buffer with Reducing Agent | Coomassie blue and Phenol red | DCP-LDSSBRA4X_50 ml | 50 ml | Viewarrow_forward |
| LDS Sample Buffer with Reducing Agent | Coomassie blue and Phenol red | DCP-LDSSBRA4X_100 ml | 100 ml | Viewarrow_forward |
| LDS Sample Buffer without Reducing Agent | Coomassie blue and Phenol red | DCP-LDSSB-RA4X_25 ml | 25 ml | Viewarrow_forward |
| LDS Sample Buffer without Reducing Agent | Coomassie blue and Phenol red | DCP-LDSSB-RA4X_100 ml | 100 ml | Viewarrow_forward |
Not sure which one? Compare the four buffers side by side · See applications by buffer · Read the FAQ
What this category covers
Protein Loading and Sample Buffers play a crucial role in ensuring consistent and reliable protein separation during gel electrophoresis, facilitating accurate analysis of protein samples in various molecular biology and biochemistry applications.
- Four products, six catalog entries. SDS Gel Loading Buffer, Native Loading Buffer, LDS Sample Buffer with Reducing Agent, and LDS Sample Buffer without Reducing Agent.
- Two tracking-dye systems. The SDS and Native loading buffers carry Bromophenol Blue; both LDS sample buffers carry Coomassie blue and Phenol red.
- Reducing agent is a stocked choice, not a special order. The LDS sample buffer is cataloged in a with-reducing-agent and a without-reducing-agent version.
- Sterility. Filtered 0.1 micron twice and 0.04 micron twice, in a sterile environment.
- Fill sizes span bench to core-facility scale. 5 x 1 mL, 20 ml, 25 ml, 50 ml, and 100 ml, depending on the product.
- Customization is offered. Other concentrations, added chemicals, compounds, proteins or supplements, different pH, and other modifications are available on inquiry.
- Products in this category4
- Catalog entries (Cat. No.)6
- Concentrations offered[1]4X and 5X
- Tracking dye — SDS / NativeBromophenol Blue
- Tracking dye — LDS (both)Coomassie blue and Phenol red
- Reducing-agent options (LDS)with / without
- Pre-filtration0.1 µm × 2
- Final polish0.04 µm × 2
- Total membrane passes4
- Fill sizes across the category5 x 1 mL, 20 / 25 / 50 / 100 ml
[1] Concentration is not stated in the source description. 4X and 5X are taken from the published Diagnocine product titles — SDS Gel Loading Buffer [5X] (94044), Native Loading Buffer [5X] (94320), LDS Sample Buffer with Reducing Agent [4X] (94283), LDS Sample Buffer without Reducing Agent [4X] (94282). Confirm against the Certificate of Analysis before use.
The buffer you add before the run sets what the gel can tell you
A loading buffer is not a neutral carrier. It fixes whether proteins are denatured, whether disulfide-linked subunits stay together, how far the front has travelled, and how clean the lane looks. Each card below names one of those levers.
Denaturation sets what is being measured
In a denaturing system, dodecyl sulfate coats the unfolded polypeptide and imposes a roughly uniform charge-to-mass ratio, so migration tracks molecular weight rather than native charge or shape. This is the basis of the discontinuous SDS system in general use.[3]
The reducing agent decides subunits or complexes
A reducing sample buffer breaks inter- and intra-chain disulfide bonds, so a disulfide-linked protein resolves into its constituent chains. A non-reducing buffer leaves those bonds intact, so the complex runs as one species. This category stocks both, so the choice is a catalog choice.
The tracking dye tells you when to stop
The dye migrates ahead of most proteins and marks the position of the running front, which is how run time is judged by eye. This category carries two dye systems: Bromophenol Blue in the SDS and Native loading buffers, Coomassie blue with Phenol red in both LDS sample buffers.
Native buffers keep the protein folded
A native, non-denaturing loading buffer is formulated without dodecyl sulfate and without a reducing agent, so the protein enters the gel in its folded state and separation reflects charge, size, and shape together. That is what makes in-gel activity work possible. Confirm the exact formulation on the product page or Certificate of Analysis.[2]
Particulates cost you lanes
Every buffer in this category is filtered 0.1 micron twice and 0.04 micron twice, in a sterile environment. That specification is about what does not reach the well: undissolved solids and precipitate that would otherwise show up as streaking or a distorted front.
Concentration and format shape the workflow
A 4X or 5X concentrate is diluted into the sample, so the stock concentration sets how much sample volume you keep. Fill sizes run from 5 x 1 mL single-use vials up to 100 ml bulk, which is the difference between an occasional gel and a core-facility queue.
The one decision to get right before you order
Reducing or non-reducing. Everything else in this category can be worked around at the bench; that one cannot, because it changes what the gel shows. If you are looking at antibodies, disulfide-linked multimers, or any protein whose subunits are held together by disulfide bonds, the with-reducing-agent and without-reducing-agent versions of the LDS Sample Buffer answer two different questions — and both are stocked under their own catalog numbers.
Four developments that explain the four products on this page
The source description does not carry a chronology. The four stages below are drawn from the primary methods literature and are individually cited in the References section, so each can be checked or removed independently.
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1
1964 Discontinuous (disc) electrophoresis
Ornstein and Davis described the discontinuous, or stacking, buffer system: a low-percentage stacking gel at one pH concentrates the sample into a thin starting band before it enters the resolving gel.[1,2] This is why a loading buffer is buffered at all, rather than simply being glycerol and dye.
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2
1970 The SDS system in general use
Laemmli combined the discontinuous system with sodium dodecyl sulfate and a reducing agent, producing the denaturing method that molecular-weight estimation on a gel still rests on.[3] The SDS Gel Loading Buffer on this page belongs to that lineage.
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3
1987 Reaching the small proteins
Schägger and von Jagow replaced glycine with tricine as the trailing ion, extending clean separation down to roughly 1 kDa and making small peptides tractable on a gel.[4,5] Sample handling for low-molecular-weight work traces to this line of development.
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4
Modern practice LDS chemistry and the neutral-pH gel
Lithium dodecyl sulfate is the lithium salt of the same dodecyl sulfate anion used in SDS-PAGE; LDS sample buffers are the standard pairing for neutral-pH Bis-Tris gel systems, and they are commonly formulated with Coomassie G-250 and phenol red as tracking dyes rather than bromophenol blue.[6] Both LDS Sample Buffer entries on this page carry exactly that dye pair.
Four membrane passes before the buffer is filled
The source states one sterility specification for the category: filtered 0.1 micron twice and 0.04 micron twice, in a sterile environment. The four stages below are that statement, in order.
-
1
0.1 µm Pre-filtration I
First pass through a 0.1 micron membrane, removing bulk particulates carried in from raw materials and dissolution.
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2
0.04 µm Pre-filtration II
Second pass at 0.04 micron, a rating below the 0.1 micron stage that precedes it.
-
3
0.1 µm Sterile-filtration I
Repeat 0.1 micron pass, performed within the sterile environment in which the buffer is filled.
-
4
0.04 µm Sterile-filtration II — final polish
Final 0.04 micron polishing pass immediately before fill, in the same sterile environment.
What the specification buys you at the well
A loading buffer is added directly to the sample and goes into the well undiluted by anything else. Particulate carried in by the buffer therefore arrives at the top of the lane, where it can seed streaking and distort the front. Four membrane passes ending at 0.04 micron are aimed at that failure mode.
The four buffers side by side
Name, tracking dye, catalog number, and size are reproduced from the source catalog. Concentration comes from the published product titles[1], and the two right-hand columns describe the buffer class rather than a Diagnocine formulation — check the product page or Certificate of Analysis for the actual composition.
| Product | Cat. No. | Conc.[1] | Tracking dye | Reducing agent | Sizes | Gel system this buffer class is used with[2] |
|---|---|---|---|---|---|---|
| SDS Gel Loading Buffer | DCP-SDSLB5X | 5X | Bromophenol Blue | Not stated in source | 5 x 1 mL | Denaturing SDS-PAGE, the discontinuous Tris-glycine system[3] |
| Native Loading Buffer | DCP-NLB5X | 5X | Bromophenol Blue | cancel Native buffers are non-reducing by definition | 20 ml | Native (non-denaturing) PAGE, where folded state is preserved[2] |
| LDS Sample Buffer with Reducing Agent | DCP-LDSSBRA4X_50 ml DCP-LDSSBRA4X_100 ml |
4X | Coomassie blue and Phenol red | check_circle Yes — named in the product | 50 ml, 100 ml | Denaturing, reducing PAGE; LDS is the usual pairing for neutral-pH Bis-Tris gels[6] |
| LDS Sample Buffer without Reducing Agent | DCP-LDSSB-RA4X_25 ml DCP-LDSSB-RA4X_100 ml |
4X | Coomassie blue and Phenol red | cancel No — named in the product | 25 ml, 100 ml | Denaturing, non-reducing PAGE; disulfide-linked species stay intact[6] |
[2] The right-hand column describes what each class of loading buffer is conventionally used with, cited in the References section. It is not a Diagnocine compatibility claim for a specific catalog number.
Which buffer for which bench workflow
Select a product to see the workflows it supports. The first bullet in each panel is the source description's own statement of use; the remaining bullets are method-level workflows drawn from the cited literature and can be removed independently.
- Protein separation during gel electrophoresis, and accurate analysis of protein samples in molecular biology and biochemistry applications
- Denaturing SDS-PAGE on discontinuous Tris-glycine gels[3]
- Sample preparation ahead of western blot transfer[7]
- Apparent molecular-weight estimation against a protein ladder[3]
- Routine expression checks and fraction analysis during purification
- Protein separation during gel electrophoresis, and accurate analysis of protein samples in molecular biology and biochemistry applications
- Native (non-denaturing) PAGE, where the protein must enter the gel folded[2]
- In-gel enzyme activity work, where denaturation would destroy the readout[8]
- Separations in which native charge, size, and shape all contribute to mobility[2]
- Protein separation during gel electrophoresis, and accurate analysis of protein samples in molecular biology and biochemistry applications
- Denaturing, reducing PAGE on neutral-pH Bis-Tris gel systems[6]
- Resolving a disulfide-linked protein into its constituent chains
- Western blot sample preparation where subunit-level resolution is wanted[7]
- Protein separation during gel electrophoresis, and accurate analysis of protein samples in molecular biology and biochemistry applications
- Denaturing, non-reducing PAGE, where disulfide-linked species must stay intact[6]
- Comparing a sample side by side against its reduced counterpart on the same gel
- Work where a reducing agent would interfere with a downstream label or detection chemistry
The same sample, two different answers
Both versions of the LDS Sample Buffer are stocked because they answer different questions about the same protein. This table is a decision aid, not a specification.
| Question you are asking | LDS Sample Buffer with Reducing Agent | LDS Sample Buffer without Reducing Agent |
|---|---|---|
| Disulfide bonds during sample preparation | Reduced | Left intact |
| A disulfide-linked multi-chain protein runs as | Its separate chains | One assembled species |
| Useful for subunit molecular-weight assignment | check_circle Yes | cancel Not directly |
| Useful for confirming an intact disulfide-linked assembly | cancel Not directly | check_circle Yes |
| Tracking dye | Coomassie blue and Phenol red | Coomassie blue and Phenol red |
| Cataloged sizes | 50 ml, 100 ml | 25 ml, 100 ml |
| Catalog number | DCP-LDSSBRA4X | DCP-LDSSB-RA4X |
Frequently asked questions
The questions that come up most often when a bench protocol meets a purchase order.
Methods literature behind the buffer systems
The source description carries no citation list. The entries below support the method-level statements marked with a superscript above, and are cited so each can be checked independently.
- Ornstein L. (1964). Disc electrophoresis — I. Background and theory. Annals of the New York Academy of Sciences 121(2):321–349. — Origin of the discontinuous (stacking) buffer system. doi:10.1111/j.1749-6632.1964.tb14207.x
- Davis BJ. (1964). Disc electrophoresis — II. Method and application to human serum proteins. Annals of the New York Academy of Sciences 121(2):404–427. — The companion method paper; native, non-denaturing separation of serum proteins. doi:10.1111/j.1749-6632.1964.tb14213.x
- Laemmli UK. (1970). Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227(5259):680–685. — The discontinuous SDS-PAGE system that denaturing gel loading buffers are formulated for. doi:10.1038/227680a0
- Schägger H, von Jagow G. (1987). Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the separation of proteins in the range from 1 to 100 kDa. Analytical Biochemistry 166(2):368–379. — Tricine as trailing ion; extends clean separation to small proteins and peptides. doi:10.1016/0003-2697(87)90587-2
- Schägger H. (2006). Tricine–SDS-PAGE. Nature Protocols 1(1):16–22. — Current protocol form of the tricine system. doi:10.1038/nprot.2006.4
- Invitrogen / Thermo Fisher Scientific. NuPAGE LDS Sample Buffer (4X) — product documentation. — States that LDS sample buffer is used to prepare samples for neutral-pH Bis-Tris gel systems and is formulated with Coomassie G250 and phenol red as tracking dyes rather than bromophenol blue. No DOI is published for this source.
- Towbin H, Staehelin T, Gordon J. (1979). Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. Proceedings of the National Academy of Sciences USA 76(9):4350–4354. — The western blot transfer step that denaturing sample preparation feeds. doi:10.1073/pnas.76.9.4350
- Wittig I, Braun HP, Schägger H. (2006). Blue native PAGE. Nature Protocols 1(1):418–428. — Native electrophoresis of folded proteins and complexes, including in-gel activity work. doi:10.1038/nprot.2006.62
