Related Experiment Video
Updated: Jul 8, 2026
07:19
Preparation of Extracellular Matrix Protein Fibers for Brillouin Spectroscopy
Published on: September 15, 2016
beta Sheet structure in amyloid beta fibrils and vibrational dipolar coupling
1Departments of Pharmacology, Biochemistry and Biophysics, and Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6084, USA.
Journal of the American Chemical Society
|April 21, 2005
Summary
Infrared spectroscopy of carbon-13 labeled amyloid beta protein fibrils reveals insights into their structure. Findings support parallel beta-sheet models but suggest potential out-of-register alignments or nonstandard structures.
Area of Science:
- Biophysics
- Structural Biology
- Neuroscience
Background:
- Amyloid beta protein fibrils are implicated in neurodegenerative diseases.
- Understanding the precise structure of these fibrils is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the structural organization of amyloid beta protein fibrils using vibrational dipolar coupling.
- To test existing models of amyloid fibril structure and identify discrepancies.
Main Methods:
- Amyloid beta protein fibrils were synthesized and labeled with carbon-13 (13C) at specific positions.
- Infrared spectroscopy was employed to detect vibrational dipolar coupling between labeled sites.
Main Results:
- Vibrational dipolar coupling was detected, indicating close physical proximity of labeled residues within the fibrils.
- Results support a parallel beta-sheet structure but show weaker-than-expected coupling, suggesting potential out-of-register alignments.
- Structural differences were observed between fibrils formed by full-length amyloid beta protein and a shorter fragment (residues 10-35).
Conclusions:
- The study provides evidence supporting key aspects of proposed amyloid fibril models.
- Deviations from expected coupling suggest non-ideal residue alignment or variations in parallel sheet structure.
- Distinct structural characteristics exist between different amyloid beta protein fibril variants.
Related Concept Videos
02:15Protein and Protein Structure
Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective. They may serve in transport, storage, or membranes; or they may be toxins or enzymes. Their structures, like their functions, vary greatly. They are all, however, amino acid polymers arranged in a linear sequence.
A protein's shape is critical to its function. For example, an enzyme can...
A protein's shape is critical to its function. For example, an enzyme can...
02:21Globular and Fibrous Proteins
Many proteins can be classified into two distinct subtypes - globular or fibrous. These two types differ in their shapes and solubilities.
Globular proteins are also known as spheroproteins and typically are approximately round in shape. They contain a mix of amino acid types and contain differing sequences in their primary structures. Globular proteins have many different functions, such as enzymes, cellular messengers, and molecular transporters. These roles often require the proteins to be...
Globular proteins are also known as spheroproteins and typically are approximately round in shape. They contain a mix of amino acid types and contain differing sequences in their primary structures. Globular proteins have many different functions, such as enzymes, cellular messengers, and molecular transporters. These roles often require the proteins to be...
00:55Fibrous Proteins
Fibrous proteins are either long and narrow proteins or assemble to form long and thin structures. They contain repetitive units and usually consist of either alpha helices or beta sheets and, in rare cases, a mix of both. The amino acids in the primary structure often consist of repeating amino acid sequences. The role of fibrous proteins is primarily structural. Many are located in the extracellular matrix and are present in connective tissues to impart strength and joint mobility. They are...