# STRUCTURAL STUDIES OF CONNECTIVE TISSUES

> **NIH NIH R01** · UNIV OF MED/DENT NJ-R W JOHNSON MED SCH · 1991 · $167,567

## Abstract

The unique components intrinsic to basement membranes have been
characterized, but the 3-dimensional organization of type IV collagen and
its structural relation to other components remain to be defined.  X-ray
diffraction patterns of dried, stretched bovine lens capsule show, in
addition to high angle reflections from the type IV triple-helix, series of
4.6nm and 33.5 nm meridional reflections which suggest a surprising degree
of supramolecular order.  We propose to clarify the relation between the x-
ray data and native basement membrane structure.  The origin of the
observed repeating units in specific tissue components will be identified
through x-ray studies on selectively extracted lens capsules and on
individual components.  Electron microscopy will be done on stretched and
unstretched lens capsules, prepared by replica plating on freeze etched
specimens, and optical diffraction of electron micrographs will be compared
with x-ray diffraction patterns.  Structural information on lens capsule,
which represents a highly ordered and type IV rich basement membrane, will
provide a basis for understanding the structure and function of other
basement membranes and alterations in diseased states.

Interpretation of our basement membrane x-ray data requires a model for the
molecular conformation of type IV collagen.  The classic triple-helical
conformation found in fibrillar collagens has the stringent amino acid
constraint that every third residue must by glycine, and Gly substitution
have been associated with connective tissue diseases.  In contrast, native
type IV collagen contains more than 20 breaks in the repeating tripeptide
(X-Y-Gly)n pattern.  We hypothesize:  (1) the effect of an interruption
depends upon its general character [Gly substitution, Gly deletion, Y (or
X) deletion, or insertion]; and (2) charged pair sequences surrounding an
interruption lessen the structural consequences by allowing the peptide
chain to loop out at the site.  These hypotheses will be tested by
characterizing the conformation, stability and folding defined sequence
triple-helical peptides, including peptides with interruptions flanked by
charged triplets, using circular dichroism and NMR spectroscopy, together
with x-ray diffraction and computer modeling.  Following studies on simple
models, a peptide with a 34 residue type IV sequence which includes an
interruption will be characterized, and 2-dimensional NMR will be used to
determine the 3-dimensional conformation of a "designed" triple-helical
peptide in solution.  Results from these peptide studies will help define
perturbations to the type IV triple-helix, and clarify the structural
consequences of fibrillar collagen mutations.

## Key facts

- **NIH application ID:** 3155064
- **Project number:** 2R01AR019626-13A1
- **Recipient organization:** UNIV OF MED/DENT NJ-R W JOHNSON MED SCH
- **Principal Investigator:** BARBARA M BRODSKY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1991
- **Award amount:** $167,567
- **Award type:** 2
- **Project period:** 1977-03-01 → 1995-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3155064

## Citation

> US National Institutes of Health, RePORTER application 3155064, STRUCTURAL STUDIES OF CONNECTIVE TISSUES (2R01AR019626-13A1). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3155064. Licensed CC0.

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