# PROPERTIES OF THE 3RD AND 4TH COMPLEMENT PROTEINS

> **NIH NIH R01** · WASHINGTON UNIVERSITY · 1987 · $131,829

## Abstract

The specific aims of the research proposed here are to describe in detail
the chemical mechanism for covalent bond formation between both the third
(C3) and the fourth (C4) human complement proteins and the variety of
molecules with which they can form either acyl ester or amide bonds and to
determine the chemical nature of interactions between these proteins and
antigen and antibody molecules.

The activation of C3 and C4 and their subsequent covalent binding to immune
complexes are key steps in the processing and clearance of the complexes.
Hence, the chemical reactivity of these complement proteins with antigen
and antibody molecules is of special concern, particularly in view of the
finding that genetically different forms of C3 and C4 are known to be
associated with certain auto-immune diseases of which systemic lupus
erythematosus is an example.  Indeed, in view of our current knowledge of
the chemical and molecular properties of C3 and C4 it is appropriate at
this time to focus our attention on their interactions with antigen and
antibody molecules in relation to immune complex-mediated disease in
general.

Accordingly, we will investigate 1) the mechanism of covalent bond
formation and hydrolysis, 2) the chemical nature of covalent bonds formed
between C3 and C4 and model immune complexes composed of ovalbumin and
anti-ovalbumin, 3) the covalent interactions between C3 and C4 and DNA
antigens, 4) the covalent interactions between C3 and C4 and the capsular
polysaccharide antigen of Haemophilus influenzae, type b, and 5) the use of
anti-C4 monoclonal antibodies as probes of C4 structure and function.

## Key facts

- **NIH application ID:** 3126700
- **Project number:** 5R01AI016543-08
- **Recipient organization:** WASHINGTON UNIVERSITY
- **SAM.gov UEI:** L6NFUM28LQM5
- **Principal Investigator:** R P LEVINE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $131,829
- **Award type:** 5
- **Project period:** 1983-03-01 → 1991-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3126700

## Citation

> US National Institutes of Health, RePORTER application 3126700, PROPERTIES OF THE 3RD AND 4TH COMPLEMENT PROTEINS (5R01AI016543-08). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3126700. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*